Support tailoring clang --target flag based on min sdk version.

Bug: 215748260
Test: Tested using aquery to verify the --target flag; add added unit

Change-Id: Ifb13509db7d1e110316aa44d55ec9cccaa4b83d1

bp2build/cc_object_conversion_test.go

@@ -55,6 +55,8 @@ func TestCcObjectSimple(t *testing.T) {
         "a/b/*.c"
     ],
     exclude_srcs: ["a/b/exclude.c"],
+    sdk_version: "current",
+    min_sdk_version: "29",
 }
 `,
 		expectedBazelTargets: []string{
@@ -71,6 +73,8 @@ func TestCcObjectSimple(t *testing.T) {
     ]`,
 				"srcs":                `["a/b/c.c"]`,
 				"system_dynamic_deps": `[]`,
+        "sdk_version": `"current"`,
+        "min_sdk_version": `"29"`,
 			}),
 		},
 	})