Add GMP_INCLUDE_DIRS in a couple of places

Fixes the build on OpenBSD (trac #2009). Based on a patch from kili.

rts/package.conf.in

@@ -69,6 +69,7 @@ include-dirs:		INCLUDE_DIR GMP_INCLUDE_DIRS
 include-dirs:		FPTOOLS_TOP_ABS"/includes"
              		FPTOOLS_TOP_ABS"/rts"
              		FPTOOLS_TOP_ABS"/gmp/gmpbuild"
+             		GMP_INCLUDE_DIRS
 #endif
 
 includes:		Stg.h

utils/hsc2hs/Makefile

@@ -39,9 +39,17 @@ else
 extra_flags=
 endif
 
+nothing=
+space=$(nothing) $(nothing)
+# Given
+#   foo bar
+# make
+#   :\"-Ifoo\":\"-Ibar\"
+GMP_INCLUDE_DIRS_STRINGS = $(subst $(space),,$(foreach d,$(GMP_INCLUDE_DIRS),:\"-I$(d)\"))
+
 $(INPLACE_HS): Makefile $(FPTOOLS_TOP)/mk/config.mk
 	echo "import System.Cmd; import System.Environment; import System.Exit" > $@
-	echo "main = do args <- getArgs; rawSystem \"$(FPTOOLS_TOP_ABS)/$(GHC_HSC2HS_DIR_REL)/$(HS_PROG)\" (\"--template=$(FPTOOLS_TOP_ABS)/$(GHC_HSC2HS_DIR_REL)/template-hsc.h\":\"--cc=$(CC)\":\"--ld=$(CC)\"$(patsubst %,:\"%\",$(extra_flags)):\"--cflag=-D__GLASGOW_HASKELL__=$(ProjectVersionInt)\":\"-I$(FPTOOLS_TOP_ABS)/$(GHC_INCLUDE_DIR_REL)\":\"-I$(FPTOOLS_TOP_ABS)/gmp/gmpbuild\":args) >>= exitWith" >> $@
+	echo "main = do args <- getArgs; rawSystem \"$(FPTOOLS_TOP_ABS)/$(GHC_HSC2HS_DIR_REL)/$(HS_PROG)\" (\"--template=$(FPTOOLS_TOP_ABS)/$(GHC_HSC2HS_DIR_REL)/template-hsc.h\":\"--cc=$(CC)\":\"--ld=$(CC)\"$(patsubst %,:\"%\",$(extra_flags)):\"--cflag=-D__GLASGOW_HASKELL__=$(ProjectVersionInt)\":\"-I$(FPTOOLS_TOP_ABS)/$(GHC_INCLUDE_DIR_REL)\":\"-I$(FPTOOLS_TOP_ABS)/gmp/gmpbuild\"$(GMP_INCLUDE_DIRS_STRINGS):args) >>= exitWith" >> $@
 
 $(INPLACE_PROG): $(INPLACE_HS)
 	$(HC) --make $< -o $@