manual: Avoid name collision in libm ULP table [BZ #28956]

The 32-bit and 64-bit variants of RISC-V share the same name - "RISC-V"
- when generating the libm error table for the info pages. This
collision, and the way how the table is generated, mean that the values
in the final table for "RISC-V" may be either for the 32- or 64-bit
variant, with no indication as to which.

As an additional side-effect, this makes the build non-reproducible, as
the error table generated is dependent upon the host filesystem
implementation.

To solve this issue, the libm-test-ulps-name files for both variants
have been modified to include their word size, so as to remove the
collision and provide more accurate information in the table.

An alternative proposed was to merge the two variants' ULP values into a
single file, but this would mean that information about error values is
lost, as the two variants are not identical. Some differences are
considerable, notably the values for the exp() function are large.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

sysdeps/riscv/rv32/rvd/libm-test-ulps-name

@@ -1 +1 @@
-RISC-V
+RISC-V 32-bit

sysdeps/riscv/rv64/rvd/libm-test-ulps-name

@@ -1 +1 @@
-RISC-V
+RISC-V 64-bit