Followup for bug 1538060 - Unbust OSX ccov builds. r=me,a=CristianB

We rename the gcov_flush patch to force a rebuild of clang with the
updated patch.

build/build-clang/clang-8-android.json

@@ -47,6 +47,6 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "find_symbolizer_linux.patch",
-      "rename_gcov_flush_.patch"
+      "rename_gcov_flush.patch"
     ]
 }

build/build-clang/clang-8-linux64.json

@@ -18,7 +18,7 @@
     "patches": [
       "static-llvm-symbolizer.patch",
       "find_symbolizer_linux.patch",
-      "rename_gcov_flush_.patch",
+      "rename_gcov_flush.patch",
       "android-mangling-error.patch"
     ]
 }

build/build-clang/clang-8-macosx64.json

@@ -22,6 +22,7 @@
     "ld": "/builds/worker/workspace/build/src/clang/bin/clang",
     "patches": [
       "static-llvm-symbolizer.patch",
+      "rename_gcov_flush.patch",
       "compiler-rt-cross-compile.patch",
       "compiler-rt-no-codesign.patch"
     ]

build/build-clang/rename_gcov_flush.patch

@@ -25,3 +25,16 @@ index 9af64ed332c..bcebe303ff4 100644
      Builder.CreateCall(GCOVFlush);
      I->getParent()->splitBasicBlock(I);
    }
+diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
+index e113f9a679..b3a07b18c0 100644
+--- a/clang/lib/Driver/ToolChains/Darwin.cpp
++++ b/clang/lib/Driver/ToolChains/Darwin.cpp
+@@ -1058,7 +1058,7 @@ void Darwin::addProfileRTLibs(const ArgList &Args,
+   // runtime's functionality.
+   if (hasExportSymbolDirective(Args)) {
+     if (needsGCovInstrumentation(Args)) {
+-      addExportedSymbol(CmdArgs, "___gcov_flush");
++      addExportedSymbol(CmdArgs, "___custom_llvm_gcov_flush");
+       addExportedSymbol(CmdArgs, "_flush_fn_list");
+       addExportedSymbol(CmdArgs, "_writeout_fn_list");
+     } else {