[BZ #16195] Fix build warnings from systemtap probes in non-systemtap configurations

[BZ #16195] Fix build warnings from systemtap probes in non-systemtap configurations

Joseph pointed out in the bug report (and in an earlier thread) that
systemtap probes cause build time warnings like the following:

    ../sysdeps/ieee754/dbl-64/e_atan2.c:602:4: warning: the address of
    'p' will always evaluate as 'true' [-Waddress]

due to the fact that we're now passing non-weak variables to
LIBC_PROBE in the libm probes.  This happens only on configurations
that do not enable systemtap.  The macro definition of LIBC_PROBE in
this case only acts as a sanity checker to ensure that the number
parameters passed to LIBC_PROBE is equal to the argument count
parameter passed before it.  This can be done in a much simpler manner
by just adding a macro definition for each number of arguments.  I am
assuming here that we don't really want to bother with supporting
LIBC_PROBE with an indeterminate number of arguments and if there is a
need for a probe to have more data than what is currently supported (4
arguments), one could simply add an additional macro here.