linkers: Add get_base_link_args method to static linkers

MSVC needs an argument to static linkers for doing LTO, so we need a way
for the static linker to tell us that.

mesonbuild/backend/ninjabackend.py

@@ -2467,7 +2467,9 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
         # Add linker args for linking this target derived from 'base' build
         # options passed on the command-line, in default_options, etc.
         # These have the lowest priority.
-        if not isinstance(target, build.StaticLibrary):
+        if isinstance(target, build.StaticLibrary):
+            commands += linker.get_base_link_args(self.get_base_options_for_target(target))
+        else:
             commands += compilers.get_base_link_args(self.get_base_options_for_target(target),
                                                      linker,
                                                      isinstance(target, build.SharedModule))

mesonbuild/linkers.py

@@ -33,6 +33,10 @@ class StaticLinker:
         """
         return mesonlib.is_windows()
 
+    def get_base_link_args(self, options: 'OptionDictType') -> typing.List[str]:
+        """Like compilers.get_base_link_args, but for the static linker."""
+        return []
+
     def get_exelist(self) -> typing.List[str]:
         return self.exelist.copy()