dtc: Enable and fix -Wpointer-arith warnings

This patch turns on the -Wpointer-arith option in the dtc Makefile,
and fixes the resulting warnings due to using (void *) in pointer
arithmetic.  While convenient, pointer arithmetic on void * is not
portable, so it's better that we avoid it, particularly in libfdt.

Also add necessary definition of uintptr_t needed by David Gibson's
changeset "dtc: Enable and fix -Wpointer-arith warnings" (the definition
comes from stdint.h, which u-boot doesn't have). -- gvb

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>

include/libfdt_env.h

diff --git a/include/libfdt_env.h b/include/libfdt_env.h
index a7fd2f8..671c3a8 100644
--- a/include/libfdt_env.h
+++ b/include/libfdt_env.h
@@ -38,4 +38,16 @@
 #define fdt64_to_cpu(x)		__be64_to_cpu(x)
 #define cpu_to_fdt64(x)		__cpu_to_be64(x)
 
+/*
+ * 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 /* _LIBFDT_ENV_H */