[Patch, Fortran] Implement Unsigned for SUM and PRODUCT

[Thomas Koenig]

Hello world,

this implements SUM and PRODUCT for UNSIGNED.  This is actually
missing from 24-116.txt, but that is due to an oversight.
This patch is on top of

https://gcc.gnu.org/pipermail/fortran/2024-September/060975.html

and uses the same method suggested by Richard: Use unsigned for the
data in SUM and PRODUCT in the integer library version, and call
the integer library version for unsigned.

Regression-tested. OK for trunk?

Best regards

	Thomas

gcc/fortran/ChangeLog:

	* gfortran.texi: Document SUM and PRODUCT.
	* iresolve.cc (resolve_transformational): New argument,
	use_integer, to translate calls to unsigned to calls to
	integer.
	(gfc_resolve_product): Use it
	(gfc_resolve_sum): Use it.
	* simplify.cc (init_result_expr): Handle BT_UNSIGNED.

libgfortran/ChangeLog:

	* generated/product_c10.c: Regenerated.
	* generated/product_c16.c: Regenerated.
	* generated/product_c17.c: Regenerated.
	* generated/product_c4.c: Regenerated.
	* generated/product_c8.c: Regenerated.
	* generated/product_i1.c: Regenerated.
	* generated/product_i16.c: Regenerated.
	* generated/product_i2.c: Regenerated.
	* generated/product_i4.c: Regenerated.
	* generated/product_i8.c: Regenarated.
	* generated/product_r10.c: Regenerated.
	* generated/product_r16.c: Regenerated.
	* generated/product_r17.c: Regenerated.
	* generated/product_r4.c: Regenerated.
	* generated/product_r8.c: Regenarated.
	* generated/sum_c10.c: Regenerated.
	* generated/sum_c16.c: Regenerated.
	* generated/sum_c17.c: Regenerated.
	* generated/sum_c4.c: Regenerated.
	* generated/sum_c8.c: Regenerated.
	* generated/sum_i1.c: Regenerated.
	* generated/sum_i16.c: Regenerated.
	* generated/sum_i2.c: Regenerated.
	* generated/sum_i4.c: Regenerated.
	* generated/sum_i8.c: Regenerated.
	* generated/sum_r10.c: Regenerated.
	* generated/sum_r16.c: Regenerated.
	* generated/sum_r17.c: Regenerated.
	* generated/sum_r4.c: Regenerated.
	* generated/sum_r8.c: Regenerated.
	* m4/ifunction.m4: Whitespace fix.
	* m4/product.m4: If type is integer, change to unsigned.
	* m4/sum.m4: Likewise.