[Pal] Remove redundant HOST_DIR definitions in Makefiles

Pal/src/Makefile

@@ -14,12 +14,12 @@ pal_lib_post =
 pal_static =
 pal_gdb =
 
-include host/$(PAL_HOST)/Makefile.am
-
 HOST_DIR = host/$(PAL_HOST)
 LIB_DIR = $(HOST_DIR)/.lib
 OBJ_DIR = $(HOST_DIR)/.obj
 
+include host/$(PAL_HOST)/Makefile.am
+
 CFLAGS	+= -I. -I../include -I$(HOST_DIR) -I../lib
 
 ifeq ($(PROFILING),1)

Pal/src/host/Linux-SGX/Makefile.am

@@ -1,5 +1,4 @@
 # Add host-specific compilation rules here
-HOST_DIR = host/$(PAL_HOST)
 
 CFLAGS	= -Wall -fPIC -O2 -maes -std=c11 -U_FORTIFY_SOURCE \
 	  -fno-stack-protector -fno-builtin -Wtrampolines

Pal/src/host/Linux/Makefile.am

@@ -1,5 +1,4 @@
 # Add host-specific compilation rules here
-HOST_DIR = host/$(PAL_HOST)
 SEC_DIR = security/$(PAL_HOST)
 
 CFLAGS	= -Wall -fPIC -O2 -std=c11 -U_FORTIFY_SOURCE \