Rename ninja variables with Clang in the name

Rename the ninja variables that have an extraneous Clang in the name,
since there are no longer any non-Clang variables.

Bug: 68947919
Test: no change to command lines used to build mmma bionic
Change-Id: I081d5e1d423a66d55faece6cb1d265cd5e504d5f
diff --git a/cc/config/arm64_linux_host.go b/cc/config/arm64_linux_host.go
index fa0ee64..853d818 100644
--- a/cc/config/arm64_linux_host.go
+++ b/cc/config/arm64_linux_host.go
@@ -76,7 +76,7 @@
 
 func (toolchainLinuxArm64) Cflags() string {
 	// The inherited flags + extra flags
-	return "${config.Arm64ClangCflags} ${config.LinuxBionicArm64Cflags}"
+	return "${config.Arm64Cflags} ${config.LinuxBionicArm64Cflags}"
 }
 
 func (toolchainLinuxArm64) CrtBeginSharedBinary() []string {