Makefile: Explicitly set '-std=c99'

This matches the build flags that are correctly explicitly defined in where-as the Makefile is randomly picking up whatever the
system toolchain happens to default to.

Fix dmi.c while we are here to avoid a re-define of _GNU_SOURCE.

TEST=`make` with both gcc and clang.

Change-Id: I4f973927fc018510a3beaa6c4fa2f356c77c7a6e
Signed-off-by: Edward O'Callaghan <>
Reviewed-by: Stefan Reinauer <>
Reviewed-by: Sam McNally <>
Tested-by: build bot (Jenkins) <>
2 files changed