* c-common.c (c_common_init): Set up CPP arithmetic.
	* cppinit.c (cpp_create_reader): Default CPP arithmetic to
	something reasonable for the host.
	(sanity_checks): Add checks.
	(cpp_read_main_file): Call sanity_checks() from here...
	(cpp_post_options): ... not here.
	* cpplex.c (cpp_interpret_charconst): Get max_chars right.
	* cpplib.h (struct cpp_options): New member int_precision.
testsuite:
	* gcc.dg/cpp/charconst.c: Update tests.

From-SVN: r53186