fix --printsrcinfo unify arch and non-arch specific variables

This fixes the issue with --printsrcinfo that all arch specific variants
of a variable get merged into their non arch specific variant.

The .SRCINFO file ends up having $depends containing $depends_x86_64
and omitting the latter.

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

scripts/makepkg.sh.in

@@ -1476,7 +1476,7 @@ pkgbase=${pkgbase:-${pkgname[0]}}
 # check the PKGBUILD for some basic requirements
 lint_pkgbuild || exit 1
 
-if (( !SOURCEONLY )); then
+if (( !SOURCEONLY && !PRINTSRCINFO )); then
 	merge_arch_attrs
 fi