[roll] Roll llvm-project/libc Revert "[libc] Implement process_mrelease." (#117807)

Reverts llvm/llvm-project#117503

GitOrigin-RevId: 2c9d9f39d26417fce2ccf5e87fcd84ed0f379ecd
Original-Revision: dc76a123ac1d7575e8a8fc51750f35d1fe434b29
Change-Id: I82333f9f3f8b90dea71bd897d6f976739ecaee86

Author: lntue

third_party/flower

@@ -372,7 +372,7 @@
              gitsubmoduleof="fuchsia"
              path="third_party/llvm-libc/src"
              remote="https://llvm.googlesource.com/llvm-project/libc"
-             revision="b81a156be1208cc1049a990ef57b8e034397e0f2"/>
+             revision="dc76a123ac1d7575e8a8fc51750f35d1fe434b29"/>
     <project name="third_party/lz4"
              gitsubmoduleof="fuchsia"
              path="third_party/lz4"