Add the signal catcher (for SIGQUIT and SIGUSR1).

Also fix some of the thread implementation.

Change-Id: If2d1b59a149ba1ac192ad9bc74319c8dff228549
diff --git a/build/Android.common.mk b/build/Android.common.mk
index 4adf494..26e4891 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -78,6 +78,7 @@
 	src/os_linux.cc \
 	src/reference_table.cc \
 	src/runtime.cc \
+	src/signal_catcher.cc \
 	src/space.cc \
 	src/stringpiece.cc \
 	src/stringprintf.cc \