Prior versions of autoconf defined _ALL_SOURCE if _AIX was defined. But,
autoconf 2.62 version of AC_AIX defines _ALL_SOURCE along with other four
preprocessor symbols no matter if the system is AIX or not. To keep the
traditional behaviour, as well as an uniform one, across autoconf versions
AC_AIX is replaced with our own internal macro.
but it breaks aclocal execution on some systems, with the following error:
Can't locate object method "rel2abs" via package "File::Spec" at /usr/local/bin/aclocal line 256.
needed, and being able to define it if appropriate for further configure tests
as well as for the generated config file.
Introduced reentrant.m4 intended for our reentrant related autotools/m4 macros.
finds out its return type and the types of its arguments. Added definitions
for non-configure systems config files, and introduced macro sreadfrom which
will be used on udp sockets as a recvfrom() wrapper.
enough at detecting compilation errors or at least it has been properly
configured to do so. Configuration heavily depends on this capability, so
if this compiler sanity check fails the configuration process will now fail.
when function clock_gettime() is available and the monotonic timer is
also available. Otherwise, in some cases, librt or libposix4 could be used
for linking even when finally not using the clock_gettime() function due
to lack of the monotonic clock.
autoconf 2.57 usage (which is the version you have specified as the minimum
version). It's a minor change but it does clean up some warnings with newer
autoconf (specifically 2.62).
compiled with errors. This behaviour is needed for autoconf macros which
rely on the ability to compile with or without errors, and is safer than
xlc's default of failing only upon severe errors.
it fails if the macro that is being undefined is not already defined. To
make this work under all cases and be sure that at a certain point some
specific macro isn't defined we must use the following style in configure:
m4_ifdef([macro], [m4_undefine([macro])])