Revert "[infra] Roll clang to match the version used by Flutter"

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index f495361291f55085bd0827dd0433e24caba1890e..8c1818b2484047cfcb34e3d009ea8c1f912e2e8d 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -130,6 +130,17 @@ config("compiler") {
     cflags_objcc += extra_flags
   }
 
+  if (is_clang) {
+    # This is here so that all files get recompiled after a clang roll and
+    # when turning clang on or off. (defines are passed via the command line,
+    # and build system rebuild things when their commandline changes). Nothing
+    # should ever read this define.
+    defines +=
+        [ "CR_CLANG_REVISION=" + exec_script("//tools/clang/scripts/update.py",
+                                             [ "--print-revision" ],
+                                             "trim string") ]
+  }
+
   # Mac-specific compiler flags setup.
   # ----------------------------------
   if (is_mac) {
@@ -354,8 +365,7 @@ config("compiler") {
     defines += [ "HAVE_SYS_UIO_H" ]
 
     # Use gold for Android for most CPU architectures.
-    if (current_cpu == "x86" || current_cpu == "x64" || current_cpu == "arm" ||
-        current_cpu == "arm64") {
+    if (current_cpu == "x86" || current_cpu == "x64" || current_cpu == "arm") {
       ldflags += [ "-fuse-ld=gold" ]
       if (is_clang) {
         # Let clang find the ld.gold in the NDK.
@@ -365,8 +375,10 @@ config("compiler") {
     }
 
     ldflags += [
-      # Don't re-export visible symbols from libraries.
-      "-Wl,--exclude-libs,ALL",
+      # Don't allow visible symbols from libgcc or libc++ to be
+      # re-exported.
+      "-Wl,--exclude-libs=libgcc.a",
+      "-Wl,--exclude-libs=libc++_static.a",
     ]
     if (current_cpu == "arm") {
       ldflags += [
@@ -379,15 +391,9 @@ config("compiler") {
       if (current_cpu == "arm") {
         cflags += [ "--target=arm-linux-androideabi" ]
         ldflags += [ "--target=arm-linux-androideabi" ]
-      } else if (current_cpu == "arm64") {
-        cflags += [ "--target=aarch64-linux-android" ]
-        ldflags += [ "--target=aarch64-linux-android" ]
       } else if (current_cpu == "x86") {
-        cflags += [ "--target=i686-linux-androideabi" ]
-        ldflags += [ "--target=i686-linux-androideabi" ]
-      } else if (current_cpu == "x64") {
-        cflags += [ "--target=x86_64-linux-androideabi" ]
-        ldflags += [ "--target=x86_64-linux-androideabi" ]
+        cflags += [ "--target=x86-linux-androideabi" ]
+        ldflags += [ "--target=x86-linux-androideabi" ]
       }
     }
   }
@@ -477,19 +483,25 @@ config("runtime_library") {
     ]
 
     lib_dirs += [ "$android_libcpp_root/libs/$android_app_abi" ]
-
-    libs += [
-      "$android_libcpp_library",
-      "c++abi",
-      "android_support",
-    ]
-
-    if (current_cpu == "arm") {
-      libs += [ "unwind" ]
+    libs += [ "$android_libcpp_library" ]
+
+    if (current_cpu == "mipsel") {
+      libs += [
+        # ld linker is used for mips Android, and ld does not accept library
+        # absolute path prefixed by "-l"; Since libgcc does not exist in mips
+        # sysroot the proper library will be linked.
+        # TODO(gordanac): Remove once gold linker is used for mips Android.
+        "gcc",
+      ]
+    } else {
+      libs += [
+        # Manually link the libgcc.a that the cross compiler uses. This is
+        # absolute because the linker will look inside the sysroot if it's not.
+        rebase_path(android_libgcc_file),
+      ]
     }
 
     libs += [
-      "gcc",
       "c",
       "dl",
       "m",