libc/include/inttypes.h: Remove parameter name

libc/include/inttypes.h: Remove parameter name

As discussed in GCC bug 97088
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
prototypes of library functions should use reserved names, or no name
at all.

This patch removes the 'j' parameter name from
extern intmax_t  imaxabs(intmax_t);

to avoid possible clashes with user code in case someone uses
before including Newlib's inttypes.h (or uses some other conflicting
definition)

Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@st.com>