common: merge only_for_archs and noarch=yes into one.

* noarch=yes is replaced with archs=noarch
* only_for_archs= is renamed to archs=
* archs= allows the use of wildcards and negations; first matching rule applies:
  * archs="*-musl" will build the pkg only for musl-libcs
  * archs="~*-musl" will build the pkg only on non-musl-libc
  * archs="x86_64-musl ~*-musl" will build for x86_64-musl and any non-musl
    arch.
* archs= defaults to "*"

common/xbps-src/shutils/common.sh

@@ -411,7 +411,8 @@ setup_pkg() {
     fi
     makejobs="-j$XBPS_MAKEJOBS"
 
-    if [ -n "$noarch" ]; then
+    # strip whitespaces to make "  noarch  " valid too.
+    if [ "${archs// /}" = "noarch" ]; then
         arch="noarch"
     else
         arch="$XBPS_TARGET_MACHINE"

common/xbps-src/shutils/pkgtarget.sh

@@ -1,9 +1,9 @@
 # vim: set ts=4 sw=4 et:
 
 check_pkg_arch() {
-    local cross="$1" _arch f found
+    local cross="$1" _arch f match nonegation
 
-    if [ -n "$only_for_archs" ]; then
+    if [ -n "$archs" -o "${archs// /}" != "noarch" ]; then
         if [ -n "$cross" ]; then
             _arch="$XBPS_TARGET_MACHINE"
         elif [ -n "$XBPS_ARCH" ]; then
@@ -11,13 +11,16 @@ check_pkg_arch() {
         else
             _arch="$XBPS_MACHINE"
         fi
-        for f in ${only_for_archs}; do
-            if [ "$f" = "${_arch}" ]; then
-                found=1
-                break
-            fi
+        set -f
+        for f in ${archs}; do
+            set +f
+            nonegation=${f##\~*}
+            f=${f#\~}
+            case "${_arch}" in
+                $f) match=1; break ;;
+            esac
         done
-        if [ -z "$found" ]; then
+        if [ -z "$nonegation" -a -n "$match" ] || [ -n "$nonegation" -a -z "$match" ]; then
             msg_red "$pkgname: this package cannot be built for ${_arch}.\n"
             exit 2
         fi

common/xbps-src/shutils/show.sh

@@ -12,7 +12,9 @@ show_pkg() {
     for i in ${checksum}; do
         [ -n "$i" ] && echo "checksum:	$i"
     done
-    [ -n "$noarch" ] && echo "noarch:		yes"
+    for i in ${archs}; do
+        [ -n "$i" ] && echo "archs:		$i"
+    done
     echo "maintainer:	$maintainer"
     [ -n "$homepage" ] && echo "Upstream URL:	$homepage"
     [ -n "$license" ] && echo "License(s):	$license"