lbutils: don't set USE_OPENAT and USE_URANDOM

these can be set explicitly in the compiler flags,
e.g.

make CC="cc -DUSE_OPENAT=1 -DUSE_URANDOM=1"

these options, if set to 1, will cause you to use
the code as if it were running on non-linux systems
such as openbsd. of course, some differences will
still exist, but this is useful for portability
testing when compiling on linux.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/libreboot-utils/Makefile

@@ -7,6 +7,7 @@
 
 CC = cc
 HELLCC = clang
+OLDCC = $(CC) -DUSE_URANDOM=1 -DUSE_OPENAT
 
 CFLAGS = -Os -Wall -Wextra -std=c99 -pedantic -Werror
 LDFLAGS =