Accept colon separated paths with -L and -I

Accept colon separated paths with -L and -I

This allows passing colon separated paths to
  tcc_add_library_path
  tcc_add_sysinclude_path
  tcc_add_include_path

Also there are new configure variables
  CONFIG_TCC_LIBPATH
  CONFIG_TCC_SYSINCLUDE_PATHS
which define the lib/sysinclude paths all in one and can
be overridden from configure/make

For TCC_TARGET_PE semicolons (;) are used as separators

Also, \b in the path string is replaced by s->tcc_lib_path
(CONFIG_TCCDIR rsp. -B option)