Use armv7a-linux-androideabi for arm device triple.

* This is a workaround of llvm LTO bug.
* Keep using current NDK include directory path.
  NDKTriple is default ClangTriple but kept as GccTriple for arm device.

Bug: 72619014
Test: make checkbuild
Change-Id: I5dc63c99760325c60bc2da98fd6a3125cef7267d
diff --git a/cc/config/toolchain.go b/cc/config/toolchain.go
index 279ceef..7961575 100644
--- a/cc/config/toolchain.go
+++ b/cc/config/toolchain.go
@@ -68,6 +68,8 @@
 	ClangLdflags() string
 	ClangInstructionSetFlags(string) (string, error)
 
+	ndkTriple() string
+
 	YasmFlags() string
 
 	WindresFlags() string
@@ -87,6 +89,19 @@
 type toolchainBase struct {
 }
 
+func (t *toolchainBase) ndkTriple() string {
+	return ""
+}
+
+func NDKTriple(toolchain Toolchain) string {
+	triple := toolchain.ndkTriple()
+	if triple == "" {
+		// Use the clang triple if there is no explicit NDK triple
+		triple = toolchain.ClangTriple()
+	}
+	return triple
+}
+
 func (toolchainBase) InstructionSetFlags(s string) (string, error) {
 	if s != "" {
 		return "", fmt.Errorf("instruction_set: %s is not a supported instruction set", s)