stubdom: do not use realpath, new in make 3.81

diff -r 06d80308aa2e extras/mini-os/Config.mk
@@ -38,15 +38,15 @@
 # This must be before include minios.mk!
 include $(MINI-OS_ROOT)/$(TARGET_ARCH_DIR)/arch.mk
 
-extra_incl := $(foreach dir,$(EXTRA_INC),-isystem $(realpath $(MINI-OS_ROOT)/include/$(dir)))
+extra_incl := $(foreach dir,$(EXTRA_INC),-isystem $(CURDIR)/$(MINI-OS_ROOT)/include/$(dir))
 
-DEF_CPPFLAGS += -isystem $(realpath $(MINI-OS_ROOT)/include)
+DEF_CPPFLAGS += -isystem $(CURDIR)/$(MINI-OS_ROOT)/include
 DEF_CPPFLAGS += -D__MINIOS__
 
 ifeq ($(libc),y)
 DEF_CPPFLAGS += -DHAVE_LIBC
-DEF_CPPFLAGS += -isystem $(realpath $(MINI-OS_ROOT)/include/posix)
-DEF_CPPFLAGS += -isystem $(realpath $(XEN_ROOT)/tools/xenstore)
+DEF_CPPFLAGS += -isystem $(CURDIR)/$(MINI-OS_ROOT)/include/posix
+DEF_CPPFLAGS += -isystem $(CURDIR)/$(XEN_ROOT)/tools/xenstore
 endif
 
 ifneq ($(LWIPDIR),)

diff -r 06d80308aa2e stubdom/Makefile
@@ -52,7 +52,7 @@
 GCC_INSTALL = $(shell gcc -print-search-dirs | sed -n -e 's/install: \(.*\)/\1/p')
 TARGET_CPPFLAGS += -U __linux__ -U __FreeBSD__ -U __sun__
 TARGET_CPPFLAGS += -nostdinc
-TARGET_CPPFLAGS += -isystem $(abspath $(MINI_OS)/include/posix)
+TARGET_CPPFLAGS += -isystem $(CURDIR)/$(MINI_OS)/include/posix
 TARGET_CPPFLAGS += -isystem $(CROSS_PREFIX)/$(GNU_TARGET_ARCH)-xen-elf/include
 TARGET_CPPFLAGS += -isystem $(GCC_INSTALL)include
 TARGET_CPPFLAGS += -isystem $(CURDIR)/lwip-cvs/src/include