clean up skeleton code

Pal/src/Makefile.Host

@@ -1,9 +1,11 @@
-all_hosts = Linux
+all_hosts = Skeleton Linux FreeBSD
 
 ifeq ($(OS),)
 SYS := $(shell gcc -dumpmachine)
 ifeq ($(SYS),x86_64-linux-gnu)
 OS := Linux
+else ifeq ($(findstring freebsd,$(SYS)),freebsd)
+OS := FreeBSD
 else
 $(error Unsupported platform: $(SYS))
 endif

Pal/src/host/Skeleton/db_main.c

@@ -59,6 +59,7 @@ PAL_NUM _DkGetHostId (void)
     return 0;
 }
 
-void _DkGetCPUInfo (void)
+void _DkGetCPUInfo (PAL_CPU_INFO * ci)
 {
+    /* need to be implemented */
 }