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/config/toolchain.go b/cc/config/toolchain.go
index ab09751..ff556f1 100644
--- a/cc/config/toolchain.go
+++ b/cc/config/toolchain.go
@@ -82,14 +82,14 @@
 	IncludeFlags() string
 
 	ClangTriple() string
-	ToolchainClangCflags() string
-	ToolchainClangLdflags() string
-	ClangAsflags() string
-	ClangCflags() string
-	ClangCppflags() string
-	ClangLdflags() string
-	ClangLldflags() string
-	ClangInstructionSetFlags(string) (string, error)
+	ToolchainCflags() string
+	ToolchainLdflags() string
+	Asflags() string
+	Cflags() string
+	Cppflags() string
+	Ldflags() string
+	Lldflags() string
+	InstructionSetFlags(string) (string, error)
 
 	ndkTriple() string
 
@@ -136,18 +136,18 @@
 	return triple
 }
 
-func (toolchainBase) ClangInstructionSetFlags(s string) (string, error) {
+func (toolchainBase) InstructionSetFlags(s string) (string, error) {
 	if s != "" {
 		return "", fmt.Errorf("instruction_set: %s is not a supported instruction set", s)
 	}
 	return "", nil
 }
 
-func (toolchainBase) ToolchainClangCflags() string {
+func (toolchainBase) ToolchainCflags() string {
 	return ""
 }
 
-func (toolchainBase) ToolchainClangLdflags() string {
+func (toolchainBase) ToolchainLdflags() string {
 	return ""
 }
 
@@ -159,7 +159,7 @@
 	return ""
 }
 
-func (toolchainBase) ClangAsflags() string {
+func (toolchainBase) Asflags() string {
 	return ""
 }