Add default variable 'use_system_yasm%': 0

When compiling for NaCL the following build error

native_client/build/gyp_nacl all.gyp -Dgtest_target_type=executable -Dmsan=0
Updating projects from gyp files...
gyp: name 'use_system_yasm' is not defined while evaluating condition
'use_system_yasm==1' in chromium/src/third_party/libjpeg_turbo/libjpeg.gyp

Adding use_system_yasm=0 to the command line works. (use_system_yasm=1 does not work).
Adding a default to the gyp file allows the build to work without specifying the
default value for this variable.

BUG=None
TESTED=native_client/build/gyp_nacl all.gyp -Dgtest_target_type=executable -Dmsan=0 -Duse_system_yasm=0
R=kjellander@chromium.org, noel@chromium.org

Review URL: https://codereview.chromium.org/1866193002 .
1 file changed