Remove fixed search paths from autotools.

--- a/m4/package_utilies.m4	1970-01-01 01:00:01.000000000 +0100
+++ b/m4/package_utilies.m4	2020-07-07 12:41:48.871661042 +0200
@@ -23,32 +23,32 @@
     AC_PACKAGE_NEED_UTILITY($1, "$cc", cc, [C compiler])
 
     if test -z "$MAKE"; then
-        AC_PATH_PROG(MAKE, gmake,, /usr/bin:/usr/freeware/bin)
+        AC_PATH_PROG(MAKE, gmake)
     fi
     if test -z "$MAKE"; then
-        AC_PATH_PROG(MAKE, make,, /usr/bin)
+        AC_PATH_PROG(MAKE, make)
     fi
     make=$MAKE
     AC_SUBST(make)
     AC_PACKAGE_NEED_UTILITY($1, "$make", make, [GNU make])
 
     if test -z "$LIBTOOL"; then
-	AC_PATH_PROG(LIBTOOL, glibtool,, /usr/bin)
+	AC_PATH_PROG(LIBTOOL, glibtool)
     fi
     if test -z "$LIBTOOL"; then
-	AC_PATH_PROG(LIBTOOL, libtool,, /usr/bin:/usr/local/bin:/usr/freeware/bin)
+	AC_PATH_PROG(LIBTOOL, libtool)
     fi
     libtool=$LIBTOOL
     AC_SUBST(libtool)
     AC_PACKAGE_NEED_UTILITY($1, "$libtool", libtool, [GNU libtool])
 
     if test -z "$TAR"; then
-        AC_PATH_PROG(TAR, tar,, /usr/freeware/bin:/bin:/usr/local/bin:/usr/bin)
+        AC_PATH_PROG(TAR, tar)
     fi
     tar=$TAR
     AC_SUBST(tar)
     if test -z "$ZIP"; then
-        AC_PATH_PROG(ZIP, gzip,, /bin:/usr/local/bin:/usr/freeware/bin)
+        AC_PATH_PROG(ZIP, gzip)
     fi
 
     zip=$ZIP
@@ -61,25 +61,25 @@
     AC_SUBST(makedepend)
 
     if test -z "$AWK"; then
-        AC_PATH_PROG(AWK, awk,, /bin:/usr/bin)
+        AC_PATH_PROG(AWK, awk)
     fi
     awk=$AWK
     AC_SUBST(awk)
 
     if test -z "$SED"; then
-        AC_PATH_PROG(SED, sed,, /bin:/usr/bin)
+        AC_PATH_PROG(SED, sed)
     fi
     sed=$SED
     AC_SUBST(sed)
 
     if test -z "$ECHO"; then
-        AC_PATH_PROG(ECHO, echo,, /bin:/usr/bin)
+        AC_PATH_PROG(ECHO, echo)
     fi
     echo=$ECHO
     AC_SUBST(echo)
 
     if test -z "$SORT"; then
-        AC_PATH_PROG(SORT, sort,, /bin:/usr/bin)
+        AC_PATH_PROG(SORT, sort)
     fi
     sort=$SORT
     AC_SUBST(sort)
ath: <a href='/guix/log/?id=f1bc75893ee7564fb75d0b778abc5a744da291c8'>root</a>/<a href='/guix/log/gnu?id=f1bc75893ee7564fb75d0b778abc5a744da291c8'>gnu</a>/<a href='/guix/log/gnu/services?id=f1bc75893ee7564fb75d0b778abc5a744da291c8'>services</a>/<a href='/guix/log/gnu/services/vnc.scm?id=f1bc75893ee7564fb75d0b778abc5a744da291c8'>vnc.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/services/vnc.scm?id=f1bc75893ee7564fb75d0b778abc5a744da291c8&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-05-21 01:04:39 +0200'>2023-05-21</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=896a51258aa71a483d8f6be29169098de5967baa'>services: Transient inetd services inherit requirements.</a><span class='msg-avail'>...<span class='msg-tooltip'>That way, per-connection transient services such as 'sshd-123' inherit
dependencies of their "parent" ('sshd' in this example), which is more
consistent than not depending on anything.

* gnu/services/dict.scm (dicod-shepherd-service): Pass #:requirements to
'make-inetd-constructor'.
* gnu/services/messaging.scm (bitlbee-shepherd-service): Likewise.
* gnu/services/ssh.scm (openssh-shepherd-service): Likewise.
* gnu/services/vnc.scm (xvnc-shepherd-service): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-04-02 23:35:15 -0400'>2023-04-02</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=1d0158ab9036cff7737cbfb1678f876ae67c4ac2'>services: xvnc: Do not create a regular HOME directory for xvnc user.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vnc.scm (%xvnc-accounts)
[home-directory]: Define as /var/empty.
[shell]: Set to nologin, for good measures.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-10-07 15:07:48 -0400'>2022-10-07</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=00e843050012961e9cc41b003ea9271eab718541'>Revert "Revert "services: Add xvnc-service-type.""</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 0c4966160054bc50e6ab3a4ac9c9a6a1826ab5a0.  The fix appears
in the subsequent commit, for clarity.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-10-07 12:53:22 -0400'>2022-10-07</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=0c4966160054bc50e6ab3a4ac9c9a6a1826ab5a0'>Revert "services: Add xvnc-service-type."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 1c528a95cb92b7808e6603d7956185005583629f.  This broke
'guix pull', for (yet) unknown reasons.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2022-10-07 10:11:13 -0400'>2022-10-07</span></td><td><a href='/guix/commit/gnu/services/vnc.scm?id=1c528a95cb92b7808e6603d7956185005583629f'>services: Add xvnc-service-type.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/vnc.scm: New file.
* gnu/tests/vnc.scm: Likewise.
* gnu/local.mk: Register them.
</span></span></td><td>Maxim Cournoyer</td></tr>