[gimp] configure.ac: fix escaping of backslashes in compiler version string

[Ell <ell src gnome org>]

commit d97dd6413a54e41b8b0aacab7529a8a79d274de3
Author: Ell <ell_se yahoo com>
Date:   Tue Oct 29 21:26:11 2019 +0200

    configure.ac: fix escaping of backslashes in compiler version string
    
    There is one more level of unescaping...

 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 4838a63cc8..a4860d5c66 100644
--- a/configure.ac
+++ b/configure.ac
@@ -594,7 +594,7 @@ fi
 for CC_VERSION_OPT in $CC_VERSION_OPTS; do
   # We run $CC, and escape and format its output, in a single step,
   # since some shells expand escape sequences in "echo" arguments.
-  CC_VERSION="`$CC $CC_VERSION_OPT 2>&1 | sed -e 's/\\\\/\\\\\\\\/g;s/^/\\\\t/;s/$/\\\\n/' | tr -d '\n'`"
+  CC_VERSION="`$CC $CC_VERSION_OPT 2>&1 | sed -e 's/\\\\/\\\\\\\\\\\\\\\\/g;s/^/\\\\t/;s/$/\\\\n/' | tr -d 
'\n'`"
   if test $? -eq 0; then
     break
   fi