RELNOTES: Allow CROSSTOOL files to have linker flags specific to static shared libraries.

PiperOrigin-RevId: 146655595
diff --git a/third_party/com/github/bazelbuild/bazel/src/main/protobuf/crosstool_config.proto b/third_party/com/github/bazelbuild/bazel/src/main/protobuf/crosstool_config.proto
index 7279d3a..5361e82 100644
--- a/third_party/com/github/bazelbuild/bazel/src/main/protobuf/crosstool_config.proto
+++ b/third_party/com/github/bazelbuild/bazel/src/main/protobuf/crosstool_config.proto
@@ -482,6 +482,7 @@
   FULLY_STATIC = 1;
   MOSTLY_STATIC = 2;
   DYNAMIC = 3;
+  MOSTLY_STATIC_LIBRARIES = 4;
 }
 
 message LinkingModeFlags {