Remove compiler warnings when building the emulator.

This forces -Wall during the build. Note that this patch doesn't
remove all warnings, but most of the remaining ones are from upstream anyway.

Change-Id: I8808d8495e99866e156ce5780d2e3c305eab491f
diff --git a/trace.c b/trace.c
index a96f87f..9eb8f5f 100644
--- a/trace.c
+++ b/trace.c
@@ -24,6 +24,7 @@
 #include "exec-all.h"
 #include "trace.h"
 #include "varint.h"
+#include "android/utils/path.h"
 
 TraceBB trace_bb;
 TraceInsn trace_insn;