Fix nasty parallel build problem reported by Gentoo and Westermo

Independently of each other both the Gentoo project and Westermo found
an issue with massively parallel builds on monster-core-machines.  At
Westermo there are 40 core Xeon monsters that stumble when building
sysklogd.

The Gentoo bug report is here:

    https://bugs.gentoo.org/701894

The problem stems from strlcat.c and strlcpy.c being used for both
the libcompat convenience library built for libsyslog and als for
syslogd when the system does not have either of the APIs in libc,
i.e. most Linux systems with GLIBC or musl libc.

I can either rewrite the Makefile.am files to handle dependencies
better, or we just disable parallel build like this patch. There's
too few source files to gain anything from parallel build anyway.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile.am

@@ -46,3 +46,6 @@ release: distcheck
 # Workaround for systemd unit file duing distcheck
 DISTCHECK_CONFIGURE_FLAGS = --with-systemd=$$dc_install_base/$(systemd) --with-klogd
 
+# Disable parallel build in top Makefile, we might otherwise get a very
+# bizarre build problem with strlcpy.o in libcompat and for syslogd.
+.NOTPARALLEL: