"gcc --version" output is rather unreliable

...so extend 409e6a2e "gcc -dumpversion has only
MAJOR.MINOR, not MAJOR.MINOR.PATCHLEVEL" to also cope with e.g. Fedora 18 gcc's
"gcc (GCC) 4.7.2 20121109 (Red Hat 4.7.2-8)" output line.

Change-Id: Ieb5e032685da49cd7e6f0a49a0fdc137fc24fbbd

configure.ac

@@ -2929,7 +2929,7 @@ dnl  Test the gcc version
 dnl ===================================================================
 if test "$GCC" = "yes"; then
     AC_MSG_CHECKING([the GCC version])
-    _gcc_version=`$CC --version|head -n1|sed 's/^.* //g'`
+    _gcc_version=`$CC --version|head -n1|sed -e 's/^.* //g' -e 's/-[[0-9]]*)$//'`
     _gcc_major=`echo $_gcc_version | $AWK -F. '{ print \$1 }'`
     GCCVER=`echo $_gcc_version | $AWK -F. '{ print \$1*10000+\$2*100+\$3 }'`