Style fix: Add a space betwen the if statement and the opening bracket

Style fix: Add a space betwen the if statement and the opening bracket

This patch replaces every occurrence of 'if(' with 'if ('.
The ffmpeg source tree was excluded since it will disappear anyways.

Command used for this:
    find . -type d \( -name ffmpeg \) -prune -o \
            -regex '\(.*\.[hc]\|.*\.cc\)' \
            -exec sed -i -e 's/ if(/ if (/' {} \;