Remove absolute references to pwd in linux headers.

Some distributions don't have pwd at this path.

patches/linux-4.4.10/0002-absolute-pwd.diff

@@ -0,0 +1,30 @@
+diff -u a/Makefile b/Makefile
+--- a/Makefile
++++ b/Makefile
+@@ -133,7 +133,7 @@ ifneq ($(KBUILD_OUTPUT),)
+ # check that the output directory actually exists
+ saved-output := $(KBUILD_OUTPUT)
+ KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
+-								&& /bin/pwd)
++								&& pwd)
+ $(if $(KBUILD_OUTPUT),, \
+      $(error failed to create output directory "$(saved-output)"))
+ 
+@@ -924,7 +924,7 @@ ifdef CONFIG_BUILD_DOCSRC
+ 	$(Q)$(MAKE) $(build)=Documentation
+ endif
+ ifdef CONFIG_GDB_SCRIPTS
+-	$(Q)ln -fsn `cd $(srctree) && /bin/pwd`/scripts/gdb/vmlinux-gdb.py
++	$(Q)ln -fsn `cd $(srctree) && pwd`/scripts/gdb/vmlinux-gdb.py
+ endif
+ 	+$(call if_changed,link-vmlinux)
+ 
+@@ -1122,7 +1122,7 @@ _modinst_:
+ 	@rm -rf $(MODLIB)/kernel
+ 	@rm -f $(MODLIB)/source
+ 	@mkdir -p $(MODLIB)/kernel
+-	@ln -s `cd $(srctree) && /bin/pwd` $(MODLIB)/source
++	@ln -s `cd $(srctree) && pwd` $(MODLIB)/source
+ 	@if [ ! $(objtree) -ef  $(MODLIB)/build ]; then \
+ 		rm -f $(MODLIB)/build ; \
+ 		ln -s $(CURDIR) $(MODLIB)/build ; \