Add yacc and lex support

Add support for yacc (.y or .yy) and lex (.l or .ll) files.  Also
tweak locations of .o files for normal and generated sources to
makes sure they don't collide.

Change-Id: I03172cddbdc022525bf392a81d72050406b8cdb3
diff --git a/cc/util.go b/cc/util.go
index db14c74..7440c25 100644
--- a/cc/util.go
+++ b/cc/util.go
@@ -98,6 +98,7 @@
 		cFlags:      strings.Join(in.CFlags, " "),
 		conlyFlags:  strings.Join(in.ConlyFlags, " "),
 		cppFlags:    strings.Join(in.CppFlags, " "),
+		yaccFlags:   strings.Join(in.YaccFlags, " "),
 		ldFlags:     strings.Join(in.LdFlags, " "),
 		ldLibs:      strings.Join(in.LdLibs, " "),
 		incFlags:    includeDirsToFlags(in.IncludeDirs),