Implement MATMUL and DOT_PRODUCT for unsigned.

gcc/fortran/ChangeLog:

	* arith.cc (gfc_arith_uminus): Fix warning.
	(gfc_arith_minus): Correctly truncate unsigneds.
	* check.cc (gfc_check_dot_product): Handle unsigned arguments.
	(gfc_check_matmul): Likewise.
	* expr.cc (gfc_get_unsigned_expr): New function.
	* gfortran.h (gfc_get_unsigned_expr): Add prototype.
	* iresolve.cc (gfc_resolve_matmul): If using UNSIGNED, use the
	signed integer version.
	* gfortran.texi: Document MATMUL and DOT_PRODUCT for unsigned.
	* simplify.cc (compute_dot_product): Handle unsigneds.

libgfortran/ChangeLog:

	* m4/iparm.m4: Add UNSIGED if type is m.
	* m4/matmul.m4: If type is GFC_INTEGER, use GFC_UINTEGER instead.
	Whitespace fixes.
	* m4/matmul_internal.m4: Whitespace fixes.

	* generated/matmul_c10.c: Regenerated.
	* generated/matmul_c16.c: Regenerated.
	* generated/matmul_c17.c: Regenerated.
	* generated/matmul_c4.c: Regenerated.
	* generated/matmul_c8.c: Regeneraated.
	* generated/matmul_i1.c: Regenerated.
	* generated/matmul_i16.c: Regenerated.
	* generated/matmul_i2.c: Regenerated.
	* generated/matmul_i4.c: Regenerated.
	* generated/matmul_i8.c: Regenerated.
	* generated/matmul_r10.c: Regenerated.
	* generated/matmul_r16.c: Regenerated.
	* generated/matmul_r17.c: Regenerated.
	* generated/matmul_r4.c: Regenerated.
	* generated/matmul_r8.c: Regenerated.
	* libgfortran.h: Add array types for unsiged.

gcc/testsuite/ChangeLog:

	* gfortran.dg/unsigned_25.f90: New test.
	* gfortran.dg/unsigned_26.f90: New test.