Fix compilation on cygwin.

* conf/Makefile.common (STRIPFLAGS_KERNEL): Add -F elf32-i386 and
	-R .drectve on cygwin.
	* conf/i386-pc-cygwin-img-ld.sc: Merge rdata and pdata into data.
	* configure.ac: Use $(top_builddir) in TARGET_OBJ2ELF.
	(COND_CYGWIN): New condition.
	* grub-core/Makefile.am (%.mod): Set TARGET_OBJ2ELF.
	* grub-core/genmod.sh.in: Use ${TARGET_OBJ2ELF} and
	not @TARGET_OBJ2ELF@.
	* util/grub-pe2elf.c (write_symbol_table): Use pe_symtab->type and not
	type to determine whether aux is to be used.

grub-core/Makefile.am

@@ -303,7 +303,7 @@ platform_DATA += moddep.lst
 CLEANFILES += config.log syminfo.lst moddep.lst
 
 $(MOD_FILES): %.mod : genmod.sh moddep.lst %.module$(EXEEXT)
-	sh $^ $@
+	TARGET_OBJ2ELF=@TARGET_OBJ2ELF@ sh $^ $@
 platform_DATA += $(MOD_FILES)
 CLEANFILES += $(MOD_FILES)