r300g/tests: Include stdio.h.

r300g/tests: Include stdio.h.

Fix build error.

  CC       compiler/tests/r300_compiler_tests-radeon_compiler_regalloc_tests.o
compiler/tests/radeon_compiler_regalloc_tests.c: In function ‘test_runner_rc_regalloc’:
compiler/tests/radeon_compiler_regalloc_tests.c:57:3: error: implicit declaration of function ‘fprintf’ [-Werror=implicit-function-declaration]
   fprintf(stderr, "Failed to load program\n");
   ^

Signed-off-by: Vinson Lee <vlee@freedesktop.org>