Move EXCEPTION_TESTS_* out of math-tests.h

Move EXCEPTION_TESTS_* out of math-tests.h

Continuing moving macros out of math-tests.h to smaller headers
following typo-proof conventions instead of using #ifndef, this patch
moves the EXCEPTION_TESTS_* macros for individual types out to their
own sysdeps header.

As with ROUNDING_TESTS_*, there is no need to define these macros if
FE_ALL_EXCEPT == 0 and the individual exception macros are undefined;
thus, math-tests-exceptions.h headers are only needed for soft-float
ARM and RISC-V, while the other cases that defined these macros do not
need to do so (and the associated math-tests.h headers are thus
removed without needing replacement by math-tests-exceptions.h
headers).

Tested with build-many-glibcs.py.

	* sysdeps/generic/math-tests-exceptions.h: New file.
	* sysdeps/generic/math-tests.h: Include <math-tests-exceptions.h>.
	(EXCEPTION_TESTS_float): Do not define here.
	(EXCEPTION_TESTS_double): Likewise.
	(EXCEPTION_TESTS_long_double): Likewise.
	(EXCEPTION_TESTS_float128): Likewise.
	* sysdeps/arm/math-tests.h [__SOFTFP__] (EXCEPTION_TESTS_float):
	Likewise.
	[__SOFTFP__] (EXCEPTION_TESTS_double): Likewise.
	[__SOFTFP__] (EXCEPTION_TESTS_long_double): Likewise.
	* sysdeps/arm/nofpu/math-tests-exceptions.h: New file.
	* sysdeps/m68k/coldfire/math-tests.h: Remove file.
	* sysdeps/mips/math-tests.h: Likewise.
	* sysdeps/nios2/math-tests.h: Likewise.
	* sysdeps/riscv/math-tests.h [!__riscv_flen]
	(EXCEPTION_TESTS_float): Do not define here.
	[!__riscv_flen] (EXCEPTION_TESTS_double): Likewise.
	[!__riscv_flen] (EXCEPTION_TESTS_long_double): Likewise.
	* sysdeps/riscv/nofpu/math-tests-exceptions.h: New file.