Update common.h

Changed the format argument for function sscanf (using the macros defined in 'inttypes.h') since it was showing a warning when compiled with mingw: (warning: unknown conversion type character 'l' in format too many arguments for format). According to this http://sourceforge.net/p/tdm-gcc/bugs/62/ using lld/llu would not work with 64bit numbers?
This still gives a warning in mingw: (warning: ISO C++ does not support the 'I64' ms_scanf length modifier [-Wformat]). Using the -Wno-pedantic-ms-format flag removes these warnings (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25502)
Also I get a warning about flag -fPIC: warning: -fPIC ignored for target (all code is position independent) [enabled by default].