Allow implicitly enabling memprof_optimize for FDO.

This is the instrumented FDO version of unknown commit, which added this support
for AutoFDO. Similar to features such as ThinLTO, with this change we insert a
feature which allows implicitly enabling memprof_optimize for FDO targets. The
"enable_fdo_memprof_optimize" feature when present along with
"fdo_implicit_memprof_optimize" expands to the "memprof_optimize" feature.
This mechanism allows users to opt-out via --features=-memprof_optimize.

PiperOrigin-RevId: 855299865
Change-Id: Ie33df43aed2a4b228850666033f512aa17a05bc3

Author: Googler

cc/private/toolchain_config/configure_features.bzl

@@ -176,6 +176,8 @@ def configure_features(
              branch_fdo_provider.branch_fdo_mode == "llvm_cs_fdo") and
             "fdo_optimize" not in all_unsupported_features_set):
             all_features.append("fdo_optimize")
+            if "memprof_optimize" not in all_unsupported_features_set:
+                all_features.append("enable_fdo_memprof_optimize")
             if "thin_lto" not in all_unsupported_features_set:
                 all_features.append("enable_fdo_thinlto")
             if ("split_functions" not in all_unsupported_features_set and