makepkg: disable extglob when sourcing BUILDSCRIPT

PKGBUILDs are advertised as being pure bash so it would be expected
that the default bash options are in effect when sourcing it.

This inadvertantly "fixes" FS#27780 where enabling extglob causes
the bash parser to error on non-valid bash function names like
package_libxml++(). Note that these function names are unsupported
in bash and could break again even with this "fix" in future bash
releases.

Signed-off-by: Allan McRae <allan@archlinux.org>
Signed-off-by: Dan McGee <dan@archlinux.org>

scripts/makepkg.sh.in

@@ -2106,7 +2106,9 @@ if [[ ! -f $BUILDFILE ]]; then
 	else
 		# PKGBUILD passed through a pipe
 		BUILDFILE=/dev/stdin
+		shopt -u extglob
 		source "$BUILDFILE"
+		shopt -s extglob
 	fi
 else
 	crlftest=$(file "$BUILDFILE" | grep -F 'CRLF' || true)
@@ -2118,7 +2120,9 @@ else
 	if [[ ${BUILDFILE:0:1} != "/" ]]; then
 		BUILDFILE="$startdir/$BUILDFILE"
 	fi
+	shopt -u extglob
 	source "$BUILDFILE"
+	shopt -s extglob
 fi
 
 # set defaults if they weren't specified in buildfile