Makepkg missing check for empty pkgname

I thought it was wierd that makepkg didn't do a sanity check for the
$pkgname.  This makes for a simple first try at a GIT patch.

Signed-off-by: K. Piche <kevin@archlinux.org>
Signed-off-by: Dan McGee <dan@archlinux.org>

scripts/makepkg.sh.in

@@ -1288,6 +1288,10 @@ fi
 source "$BUILDSCRIPT"
 
 # check for no-no's in the build script
+if [ -z "$pkgname" ]; then
+	error "$(gettext "%s is not allowed to be empty.")" "pkgname"
+	exit 1
+fi
 if [ -z "$pkgver" ]; then
 	error "$(gettext "%s is not allowed to be empty.")" "pkgver"
 	exit 1