build: Properly generate build dependency for autogenerated bitmap .h files

 * bmp2rb generated a .h file that rockbox .c files used.
 * .h files in .c files were used to generate dependency graphs for make
 * When Make saw the .h file for the bitmap, it didn't know how what
   to do with them
 * Only arose in parallel builds

Fixed this by adding explicit dependencies for the .h files as part of
the existing 'bmpdepfile' function.

Solves the Xduoo X3 bootloader build failure that I could trigger 100%
of the time by using 'make -j8'

Change-Id: I6b3e78dde26c820a3b6c7c286e7d6c981b8e01fc

0 files changed, 0 insertions, 0 deletions