Add prefix_symbols support to cc_object

Test: add cc_object with prefix_symbols, use objdump to check
Change-Id: I15eb47e6888eb1c4837734a44a7ad86205a48c02
diff --git a/cc/cc.go b/cc/cc.go
index ea523ca..0e1d896 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -140,6 +140,9 @@
 type ObjectLinkerProperties struct {
 	// names of other cc_object modules to link into this module using partial linking
 	Objs []string `android:"arch_variant"`
+
+	// if set, add an extra objcopy --prefix-symbols= step
+	Prefix_symbols string
 }
 
 // Properties used to compile all C or C++ modules