Set the input character set, used for translation from the character set of the input file to the
source character set used by GCC. If the locale does not specify, or GCC cannot get this information
from the locale, the default is UTF-8. This can be overridden by either the locale or this command
line option. Currently the command line option takes precedence if there's a conflict. charset can
be any encoding supported by the system's "iconv" library routine.