xbps-src: make it possible to override the subpackages list via ${subpackages}.

This overrides the automatic list generated by xbps-src and it's overridable
to change the processing order of subpackages.

Manual.md

@@ -383,6 +383,10 @@ default all binaries are stripped.
 - `python_versions` A white space seperated list of python versions which will
 be used to build that package. This is only used by the `python-module` build style.
 
+- `subpackages` A white space separated list of subpackages (matching `foo_package()`)
+to override the guessed list. Only use this if a specific order of subpackages is required,
+otherwise the default would work in most cases.
+
 ### build style scripts
 
 The `build_style` variable specifies the build method to build and install a

common/environment/setup/sourcepkg.sh

@@ -7,7 +7,7 @@ unset -v only_for_archs distfiles checksum build_style nonfree
 unset -v configure_script configure_args wrksrc build_wrksrc create_wrksrc
 unset -v make_cmd make_build_args make_install_args make_build_target make_install_target python_versions
 unset -v patch_args disable_parallel_build keep_libtool_archives
-unset -v makedepends hostmakedepends depends
+unset -v subpackages makedepends hostmakedepends depends
 unset -v build_options build_options_default bootstrap
 unset -v CFLAGS CXXFLAGS CPPFLAGS LDFLAGS LD_LIBRARY_PATH
 unset -v CC CXX CPP GCC LD AR AS RANLIB NM OBJDUMP OBJCOPY STRIP READELF

common/xbps-src/shutils/common.sh

@@ -293,7 +293,9 @@ setup_pkg() {
     fi
 
     sourcepkg="${pkgname}"
+    if [ -z "$subpackages" ]; then
         subpackages="$(get_subpkgs)"
+    fi
 
     if [ -h $XBPS_SRCPKGDIR/$pkg ]; then
         # Source all subpkg environment setup snippets.