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)
>/<a href='/guix/log/nix?id=555677fdf7ea575f67eb25500a648076febe8b92'>nix</a>/<a href='/guix/log/nix/boost?id=555677fdf7ea575f67eb25500a648076febe8b92'>boost</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/nix/boost?id=555677fdf7ea575f67eb25500a648076febe8b92&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-06-24 19:55:22 +0100'>2020-06-24</span></td><td><a href='/guix/commit/nix/boost?id=cd43b55da7ab51c996a7a3449c78f2a493616106'>nix: Tweak .gitignore files.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2019-11-26 00:16:36 +0100'>2019-11-26</span></td><td><a href='/guix/commit/nix/boost?id=3a4d5ddd322c7daf0a8c83ca2c87c3fc38b19f0b'>daemon: boost::format: Fix typo "referred".</a><span class='msg-avail'>...</span></td><td>Vagrant Cascadian</td></tr>