Remove clang indirection without affecting build.ninja

Remove cflags that are not handled by clang from the global defaults,
and remove calls to ClangFilterUnknownCflags.

Squash lists of clang-specific default flags into the main default
flags lists.

Rename Toolchain.Clang*flags to Toolchain.*flags.

Rename Go variables with Clang in the name that have no non-Clang
equivalent.

Remove unused ninja variables.

Bug: 68947919
Test: no change to build.ninja for aosp_cf_x86_64_phone-userdebug or aosp_crosshatch-userdebug
Change-Id: Id287945315d53e5eaef197adbbb4f1302f2e3680
diff --git a/cc/compiler.go b/cc/compiler.go
index 69ead30..81ac035 100644
--- a/cc/compiler.go
+++ b/cc/compiler.go
@@ -392,7 +392,7 @@
 	if flags.RequiredInstructionSet != "" {
 		instructionSet = flags.RequiredInstructionSet
 	}
-	instructionSetFlags, err := tc.ClangInstructionSetFlags(instructionSet)
+	instructionSetFlags, err := tc.InstructionSetFlags(instructionSet)
 	if err != nil {
 		ctx.ModuleErrorf("%s", err)
 	}
@@ -437,10 +437,10 @@
 	flags.Global.ConlyFlags = append([]string{"${config.CommonGlobalConlyflags}"}, flags.Global.ConlyFlags...)
 	flags.Global.CppFlags = append([]string{fmt.Sprintf("${config.%sGlobalCppflags}", hod)}, flags.Global.CppFlags...)
 
-	flags.Global.AsFlags = append(flags.Global.AsFlags, tc.ClangAsflags())
+	flags.Global.AsFlags = append(flags.Global.AsFlags, tc.Asflags())
 	flags.Global.CppFlags = append([]string{"${config.CommonClangGlobalCppflags}"}, flags.Global.CppFlags...)
 	flags.Global.CommonFlags = append(flags.Global.CommonFlags,
-		tc.ClangCflags(),
+		tc.Cflags(),
 		"${config.CommonClangGlobalCflags}",
 		fmt.Sprintf("${config.%sClangGlobalCflags}", hod))
 
@@ -458,11 +458,11 @@
 
 	flags.Global.AsFlags = append(flags.Global.AsFlags, "-D__ASSEMBLY__")
 
-	flags.Global.CppFlags = append(flags.Global.CppFlags, tc.ClangCppflags())
+	flags.Global.CppFlags = append(flags.Global.CppFlags, tc.Cppflags())
 
 	flags.Global.YasmFlags = append(flags.Global.YasmFlags, tc.YasmFlags())
 
-	flags.Global.CommonFlags = append(flags.Global.CommonFlags, tc.ToolchainClangCflags())
+	flags.Global.CommonFlags = append(flags.Global.CommonFlags, tc.ToolchainCflags())
 
 	cStd := config.CStdVersion
 	if String(compiler.Properties.C_std) == "experimental" {