When 'newlib' was introduced, in the commit referenced
below, the use of that glibc '__BEGIN_DECLS' macro was
standardized. However, as issue #88 revealed, this may
result in a fatal build error with other environments.
So, this patch just trades that macro for the standard
'#ifdef __cplusplus' conventions (thus avoiding use of
all those '#include <features.h>' directives as well).
Reference(s):
. newlib introduced
commit a410e236ab
. procps-ng-3.3.13 issue
https://gitlab.com/procps-ng/procps/issues/88
. some additional discussion
https://www.freelists.org/post/procps/PATCH-Replace-glibcspecific-macros-in-procnumah,1
. musl wiki (see: sys/cdefs.h error messages)
https://wiki.musl-libc.org/faq.html
Signed-off-by: Jim Warner <james.warner@comcast.net>