Use uint32_t sign in single precision math error handling functions

Ideally sign should be bool, but sometimes (e.g. in powf) it's more
efficient to pass a non-zero value than 1 to indicate that the sign
should be set.  The fixed size int is less ambigous than unsigned
long.

	* sysdeps/ieee754/flt-32/e_powf.c (__powf): Use uint32_t.
	(exp2f_inline): Likewise.
	* sysdeps/ieee754/flt-32/math_config.h (__math_oflowf): Likewise.
	(__math_uflowf): Likewise.
	(__math_may_uflowf): Likewise.
	(__math_divzerof): Likewise.
	(__math_invalidf): Likewise.
	* sysdeps/ieee754/flt-32/math_errf.c (xflowf): Likewise.
	(__math_oflowf): Likewise.
	(__math_uflowf): Likewise.
	(__math_may_uflowf): Likewise.
	(__math_divzerof): Likewise.
	(__math_invalidf): Likewise.