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)
>
<div class='path'>path: <a href='/guix/log/?id=baaf7c0008612d88313c6491a3b7dc5c3c3beb95'>root</a>/<a href='/guix/log/gnu?id=baaf7c0008612d88313c6491a3b7dc5c3c3beb95'>gnu</a>/<a href='/guix/log/gnu/installer?id=baaf7c0008612d88313c6491a3b7dc5c3c3beb95'>installer</a>/<a href='/guix/log/gnu/installer/proxy.scm?id=baaf7c0008612d88313c6491a3b7dc5c3c3beb95'>proxy.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/installer/proxy.scm?id=baaf7c0008612d88313c6491a3b7dc5c3c3beb95&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/proxy.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/substitutes.scm: New file.
* gnu/installer/newt/substitutes.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* po/guix/POTFILES.in: Add gnu/installer/newt/substitutes.scm.
* gnu/installer/proxy.scm (with-silent-shepherd): Move to ...
* gnu/installer/utils.scm: ... here.
* gnu/installer/record.scm (&lt;installer&gt;)[substitutes-page]: New field.
* gnu/installer/newt.scm (substitutes-page): New procedure,
(newt-installer): register it.
* gnu/installer.scm (installer-steps): Add "substitutes-page" step.
* gnu/system/install.scm (%installation-services): Add avahi-service-type and
enable substitute server discover in guix-service-type.
[&lt;name-service-switch&gt;]: Set it to %mdns-host-lookup-nss.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-04-08 10:24:02 +0200'>2020-04-08</span></td><td><a href='/guix/commit/gnu/installer/proxy.scm?id=ee0ad7803c82383ac1bced073d8670bc407797e7'>installer: Add proxy support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/proxy.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add it.
* po/guix/POTFILES.in: Add it.
* gnu/installer/newt/parameters.scm (run-proxy-page): New procedure,
(run-parameters-page): add the previous procedure to the parameters menu.
</span></span></td><td>Mathieu Othacehe</td></tr>