Save deps when asflags contains -xassembler-with-cpp

Usually, ".S" files are processes with the c preprocessor, and ".s"
files are not, so they don't have any dependency information, since it
is generated by the preprocessor.

But with the -xassembler-with-cpp flag, ".s" files are processed with
the preprocessor, so we should ask for dependency information from them.

Test: NINJA_ARGS="-t deps out/soong/.intermediates/external/sonivox/arm-wt-22k/libsonivox/android_arm_armv7-a-neon_core_static/obj/external/sonivox/arm-wt-22k/lib_src/ARM-E_filter_gnu.o" m
Test: treehugger
Change-Id: Iee7baeebc2b205b5a2f33e7c1705ea4a5b4fc95a
diff --git a/cc/builder.go b/cc/builder.go
index 00dc742..554706c 100644
--- a/cc/builder.go
+++ b/cc/builder.go
@@ -271,6 +271,8 @@
 	sAbiDump        bool
 	emitXrefs       bool
 
+	assemblerWithCpp bool
+
 	systemIncludeFlags string
 
 	groupStaticLibs bool
@@ -428,7 +430,9 @@
 
 		switch srcFile.Ext() {
 		case ".s":
-			rule = ccNoDeps
+			if !flags.assemblerWithCpp {
+				rule = ccNoDeps
+			}
 			fallthrough
 		case ".S":
 			ccCmd = "clang"