Fix ldbl-128 lrintl, lroundl missing exceptions for 32-bit long (bug 19085).

The ldbl-128 implementations of lrintl and lroundl miss "invalid"
exceptions on systems with 32-bit long for arguments that overflow
long but have exponent below 48.  This patch fixes this by rearranging
the sequence of tests in the code so the exponent < 48 case is only
used for exponents that don't overflow long.

Tested for mips64 (n32 and n64).

	[BZ #19085]
	* sysdeps/ieee754/ldbl-128/s_lrintl.c (__lrintl): Move test for
	exponent below 48 inside case for non-overflowing exponent.
	* sysdeps/ieee754/ldbl-128/s_lroundl.c (__lroundl): Likewise.