Update zm_jpeg.cpp

Change 0 to FALSE in order to avoid compiling error on Debian Wheezy:

[ 31%] Building CXX object src/CMakeFiles/zm.dir/zm_image.cpp.o
/opt/ZoneMinder/src/zm_image.cpp: In member function ‘bool Image::WriteJpeg(const char*, int) const’:
/opt/ZoneMinder/src/zm_image.cpp:863:42: error: cannot convert ‘bool’ to ‘boolean’ for argument ‘3’ to ‘void jpeg_set_quality(j_compress_ptr, int, boolean)’
/opt/ZoneMinder/src/zm_image.cpp: In member function ‘bool Image::EncodeJpeg(JOCTET*, int*, int) const’:
/opt/ZoneMinder/src/zm_image.cpp:1096:42: error: cannot convert ‘bool’ to ‘boolean’ for argument ‘3’ to ‘void jpeg_set_quality(j_compress_ptr, int, boolean)’
make[2]: *** [src/CMakeFiles/zm.dir/zm_image.cpp.o] Error 1
make[1]: *** [src/CMakeFiles/zm.dir/all] Error 2
make: *** [all] Error 2