compiler.h: unify system ifdef cruft here

Shove a lot of the HOSTCC and related #ifdef checking crap into the new
compiler.h header so that we can keep all other headers nice and clean.

Also introduce custom uswap functions so we don't have to rely on the non
standard implementations that a host may (or may not in the case of OS X)
provide.  This allows mkimage to finally build cleanly on an OS X system.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/libfdt_env.h b/include/libfdt_env.h
index 1c67015..bf63583 100644
--- a/include/libfdt_env.h
+++ b/include/libfdt_env.h
@@ -21,56 +21,13 @@
 #ifndef _LIBFDT_ENV_H
 #define _LIBFDT_ENV_H
 
-#ifdef USE_HOSTCC
-#include <stdint.h>
-#include <string.h>
-#ifdef __MINGW32__
-#include <linux/types.h>
-#include <linux/byteorder/swab.h>
-#else
-#include <endian.h>
-#include <byteswap.h>
-#endif /* __MINGW32__ */
-#else
-#include <linux/string.h>
-#include <linux/types.h>
-#include <asm/byteorder.h>
-#endif /* USE_HOSTCC */
+#include "compiler.h"
 
-#include <stddef.h>
 extern struct fdt_header *working_fdt;  /* Pointer to the working fdt */
 
-#if __BYTE_ORDER == __LITTLE_ENDIAN
-#ifdef __MINGW32__
-#define fdt32_to_cpu(x)		___swab32(x)
-#define cpu_to_fdt32(x)		___swab32(x)
-#define fdt64_to_cpu(x)		___swab64(x)
-#define cpu_to_fdt64(x)		___swab64(x)
-#else
-#define fdt32_to_cpu(x)		bswap_32(x)
-#define cpu_to_fdt32(x)		bswap_32(x)
-#define fdt64_to_cpu(x)		bswap_64(x)
-#define cpu_to_fdt64(x)		bswap_64(x)
-#endif
-#else
-#define fdt32_to_cpu(x)		(x)
-#define cpu_to_fdt32(x)		(x)
-#define fdt64_to_cpu(x)		(x)
-#define cpu_to_fdt64(x)		(x)
-#endif
-
-#ifndef USE_HOSTCC
-/*
- * Types for `void *' pointers.
- *
- * Note: libfdt uses this definition from /usr/include/stdint.h.
- * Define it here rather than pulling in all of stdint.h.
- */
-#if __WORDSIZE == 64
-typedef unsigned long int       uintptr_t;
-#else
-typedef unsigned int            uintptr_t;
-#endif
-#endif /* not USE_HOSTCC */
+#define fdt32_to_cpu(x)		be32_to_cpu(x)
+#define cpu_to_fdt32(x)		cpu_to_be32(x)
+#define fdt64_to_cpu(x)		be64_to_cpu(x)
+#define cpu_to_fdt64(x)		cpu_to_be64(x)
 
 #endif /* _LIBFDT_ENV_H */