Move android_get_control_socket out of line

android_get_control_socket has a warning from the implicit cast from
long to int.  The warning was being hidden because cutils/sockets.h was
included with -isystem.  Move android_get_control_socket to sockets.cpp,
since we don't want header only dependencies anyways, and fix the
warning with a range check and a static_cast.

Bug: 31492149
Test: m -j <module that uses sockets.h and -Wall>
Change-Id: I1f394ab26d4ec8a7dd0e7907c10416d7f8647624
diff --git a/lmkd/Android.mk b/lmkd/Android.mk
index 8c88661..8980d1c 100644
--- a/lmkd/Android.mk
+++ b/lmkd/Android.mk
@@ -2,7 +2,7 @@
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES := lmkd.c
-LOCAL_SHARED_LIBRARIES := liblog libm libc libprocessgroup
+LOCAL_SHARED_LIBRARIES := liblog libm libc libprocessgroup libcutils
 LOCAL_CFLAGS := -Werror
 
 LOCAL_MODULE := lmkd