Introduce "broken" var to skip building broken packages; make "nocross" not error out.

- broken var simply exits (without error) and skips building a pkg.
- nocross var now simply exits without an error, to make buildbot continue building pkgs.

Manual.md

@@ -384,7 +384,7 @@ by all supported architectures.
 - `nostrip` If set, the ELF binaries with debugging symbols won't be stripped. By
 default all binaries are stripped.
 
-- `nocross` If set, cross compilation won't be allowed and will exit with an error.
+- `nocross` If set, cross compilation won't be allowed and will exit immediately.
 
 - `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.
@@ -393,6 +393,8 @@ be used to build that package. This is only used by the `python-module` build st
 to override the guessed list. Only use this if a specific order of subpackages is required,
 otherwise the default would work in most cases.
 
+- `broken` If set, building the package won't be allowed because its state is currently broken.
+
 ### build style scripts
 
 The `build_style` variable specifies the build method to build and install a

common/environment/setup/sourcepkg.sh

@@ -3,7 +3,7 @@
 
 ## VARIABLES
 unset -v pkgname version revision short_desc homepage license maintainer
-unset -v only_for_archs distfiles checksum build_style nonfree nocross
+unset -v only_for_archs distfiles checksum build_style nonfree nocross broken
 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

common/xbps-src/shutils/common.sh

@@ -389,7 +389,11 @@ setup_pkg() {
     fi
 
     if [ "$cross" -a "$nocross" ]; then
-        msg_error "$pkgver: cannot be cross compiled, exiting...\n"
+        msg_red "$pkgver: cannot be cross compiled, exiting...\n"
+        exit 0
+    elif [ "$broken" ]; then
+        msg_red "$pkgver: cannot be built, it's currently broken; exiting...\n"
+        exit 0
     fi
 }