Change POSIX macros to avoid exit and abort

I found that the BREAK_* macros behaved differently on POSIX and in
some cases this was causing a brutal exit of POSIX meterpteter in
cases where it should just gracefully fail.

After talking to egypt, we decided to use `break` statements instead
given that's how it should function.

c/meterpreter/source/extensions/stdapi/server/precomp.h

@@ -39,16 +39,16 @@
 #define WSAECONNABORTED ECONNABORTED
 
 #define BREAK_WITH_ERROR(format, args...) \
-	do { \
+	{ \
 		dprintf(format, ## args); \
-		exit(0); \
-	} while(0) \
+		break; \
+	} \
 
 #define BREAK_ON_WSAERROR(format, args...) \
-	do { \
+	{ \
 		dprintf(format, ## args); \
-		abort(); \
-	} while(0) \
+		break; \
+	} \
 
 #define Sleep(x) usleep(x * 1000)
 #define WSASocket(a,b,c,d,e,f) socket(a,b,c)