When building ninja with a updated gcc compiler in a non-standard location it will throw an error saying that it cannot find some library symbols. This has now been managed by setting the runtime path in the LDFLAGS when building ninja.

Respectively invoke `ninja test` and `ninja` in meson build directory.
pb_meson_build is particularly useful if a time consuming action happens
whenever `ninja install is invoked.

Also add pb_cflags, pb_cppflags and pb_linkopts patterns

This patch also check if the configure_flags have changed and trigger a
reconfiguration if it is needed.

It is an issue on the RTPCs SL6 OS with NFS mounted volumes.