envconfig: add pkg_config_path property

In order to unify the use of sysroot in the cross-file,
the pkg_config_path can now be passed directly in the file.

docs/markdown/Cross-compilation.md

@@ -138,6 +138,7 @@ has_function_printf = true
 c_args = ['-DCROSS=1', '-DSOMETHING=3']
 c_link_args = ['-some_link_arg']
 sys_root = '/some/path'
+pkg_config_libdir = '/some/path/lib/pkgconfig'
 ```
 
 In most cases you don't need the size and alignment settings, Meson
@@ -153,7 +154,8 @@ single string (i.e. not as `'-DCROSS=1 -DSOMETHING=3'`).
 system path (the system that will run the compiled binaries). This is used
 internally by Meson to set the PKG_CONFIG_SYSROOT_DIR environment variable
 for pkg-config. If this is unset the host system is assumed to share a root
-with the build system.
+with the build system. The 'pkg_config_libdir' property may point to a list
+of path used by pkg-config to get the cross build dependencies.
 
 One important thing to note, if you did not define an `exe_wrapper` in
 the previous section, is that Meson will make a best-effort guess at

mesonbuild/dependencies/base.py

@@ -693,10 +693,15 @@ def _call_pkgbin(self, args, env=None):
         sysroot = self.env.properties[self.for_machine].get_sys_root()
         if sysroot:
             env['PKG_CONFIG_SYSROOT_DIR'] = sysroot
-        new_pkg_config_path = ':'.join([p for p in extra_paths])
+        new_pkg_config_path = os.pathsep.join([p for p in extra_paths])
         mlog.debug('PKG_CONFIG_PATH: ' + new_pkg_config_path)
         env['PKG_CONFIG_PATH'] = new_pkg_config_path
 
+        pkg_config_libdir_prop = self.env.properties[self.for_machine].get_pkg_config_libdir()
+        if pkg_config_libdir_prop:
+            new_pkg_config_libdir = os.pathsep.join([p for p in pkg_config_libdir_prop])
+            env['PKG_CONFIG_LIBDIR'] = new_pkg_config_libdir
+
         fenv = frozenset(env.items())
         targs = tuple(args)
         cache = PkgConfigDependency.pkgbin_cache

mesonbuild/envconfig.py

@@ -140,6 +140,9 @@ def get_root(self) -> T.Optional[T.Union[str, T.List[str]]]:
     def get_sys_root(self) -> T.Optional[T.Union[str, T.List[str]]]:
         return self.properties.get('sys_root', None)
 
+    def get_pkg_config_libdir(self) -> T.Optional[T.Union[str, T.List[str]]]:
+        return self.properties.get('pkg_config_libdir', None)
+
     def __eq__(self, other: T.Any) -> 'T.Union[bool, NotImplemented]':
         if isinstance(other, type(self)):
             return self.properties == other.properties