Refactor common Reactor implementations

Some functions in LLVMReactor.cpp and SubzeroReactor.cpp were identical
and have been moved into a common Reactor.cpp.

Bug swiftshader:21

Change-Id: Ib079757f9e35f83b1103e2791227f02775e034d3
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27068
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/src/Android.mk b/src/Android.mk
index 84db826..c6da7c9 100644
--- a/src/Android.mk
+++ b/src/Android.mk
@@ -61,6 +61,7 @@
 	Main/SwiftConfig.cpp
 
 COMMON_SRC_FILES += \
+	Reactor/Reactor.cpp \
 	Reactor/Routine.cpp \
 	Reactor/Debug.cpp \
 	Reactor/DebugAndroid.cpp \