scons: wait on subprocess' completion

Windows doesn't allow you to move a file that's opened, and Popen()
doesn't wait on its subprocess' completion before returning, which leads
to broken Windows build.

Fixes: 3fd425aed764fb771f2f "build systems: uniformize git_sha1.h generation"
Suggested-by: Scott D Phillips <scott.d.phillips@intel.com>
Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
1 file changed