Changes for recent gcc

[henrychoi]

Just now, I almost built the latest emcraft u-boot for cortex m3 using gcc 5.2 with just a few changes:

1. No inline in front of the stub functions pointed to by weak alias attribute (LED stuff, and show_progress).
2. nonconstant origin expression in u-boot.lds, which was discussed in another (closed) thread.

Since the u-boot does not run after Linux starts, building u-boot with the more recent toolchain is not super-important. It's just that being able to build EVERYTHING within Buildroot (using 2015.11.rc3), in 1-go, would be quite clean.