autoconf option to explicitly set ac_tool_prefix

[Richard Mlynarik]

Sometimes when cross-compiling, or when just plain compiling, it is
desirable to use a particular compiler version ot particular set of
cross-compiling tools.

The following simple --tool-prefix patch allows one to specify
  --tool-prefix=/build/v3.14/mips-linux-
and then have gcc, ld, etc searched for starting with that prefix.

This is a more general than the existing default of only prepending
$host_alias, and it allows use of tools which aren't on a directory in
$PATH which can make the build process more predictable.


Index: general.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/general.m4,v
retrieving revision 1.811
diff -U3 -w -u -r1.811 general.m4
--- general.m4  12 Nov 2002 10:54:46 -0000      1.811
+++ general.m4  18 Nov 2002 20:02:36 -0000
@@ -814,6 +814,13 @@
   -target=* | --target=* | --targe=* | --targ=* | --tar=* | --ta=* | --t=*)
     target_alias=$ac_optarg ;;
 
+  -tool-prefix | --tool-prefix | --tool-prefi | --tool-pre | \
+  | --tool-pr | --tool-p)
+    ac_prev=tool_prefix ;;
+  -tool-prefix=* | --tool-prefix=* | --tool-prefi=* | --tool-pre=* | \
+  | --tool-pr=* | --tool-p=*)
+    ac_tool_prefix=$ac_optarg ;;
+
   -v | -verbose | --verbose | --verbos | --verbo | --verb)
     verbose=yes ;;
 
@@ -926,8 +933,10 @@
   fi
 fi
 
+if test "x$ac_tool_prefix" == x; then
 ac_tool_prefix=
 test -n "$host_alias" && ac_tool_prefix=$host_alias-
+fi
 
 test "$silent" = yes && exec AS_MESSAGE_FD>/dev/null