Use correct flags for host-side assembly

BUG: 67434336
Test: Built libjpeg-turbo, confirmed flags
Change-Id: I54c1cc968d0a08d3a221ef4c46f2572269420c6a
diff --git a/cc/config/x86_darwin_host.go b/cc/config/x86_darwin_host.go
index 3f079a4..6d361b5 100644
--- a/cc/config/x86_darwin_host.go
+++ b/cc/config/x86_darwin_host.go
@@ -159,6 +159,8 @@
 		strings.Join(ClangFilterUnknownCflags(darwinX8664Cflags), " "))
 	pctx.StaticVariable("DarwinX86ClangLdflags", strings.Join(darwinX86ClangLdflags, " "))
 	pctx.StaticVariable("DarwinX8664ClangLdflags", strings.Join(darwinX8664ClangLdflags, " "))
+	pctx.StaticVariable("DarwinX86YasmFlags", "-f macho -m x86")
+	pctx.StaticVariable("DarwinX8664YasmFlags", "-f macho -m amd64")
 }
 
 func xcrun(config android.Config, args ...string) (string, error) {
@@ -276,6 +278,14 @@
 	return "${config.DarwinClangLdflags} ${config.DarwinX8664ClangLdflags}"
 }
 
+func (t *toolchainDarwinX86) YasmFlags() string {
+	return "${config.DarwinX86YasmFlags}"
+}
+
+func (t *toolchainDarwinX8664) YasmFlags() string {
+	return "${config.DarwinX8664YasmFlags}"
+}
+
 func (t *toolchainDarwin) ShlibSuffix() string {
 	return ".dylib"
 }