Setting this value using ?= caused some trouble if it was already
defined in the environment.
Originally committed as revision 19418 to svn://svn.ffmpeg.org/ffmpeg/trunk
echo "STRIP=$strip" >> config.mak ||
echo "STRIP=echo ignoring strip" >> config.mak
-echo "CPPFLAGS?=$CPPFLAGS" >> config.mak
+echo "CPPFLAGS=$CPPFLAGS" >> config.mak
echo "CFLAGS=$CFLAGS" >> config.mak
echo "ASFLAGS=$ASFLAGS" >> config.mak
echo "CC_O=$CC_O" >> config.mak