Build: Fix modules getting their optimization setting overridden.

Asterisk modules that use PJPROJECT services have their compiler
optimization and possibly their symbolic debug options overridden by the
PJPROJECT configure script selected settings.

* We need to filter-out any -O and -g options in PJ_CFLAGS before echoing
out the result so the PJPROJECT_INCLUDE variable does not override the
Asterisk module settings when using bundled PJPROJECT.

NOTE: This patch only has an effect when using bundled PJPROJECT.

ASTERISK-27563

Change-Id: If124169735ecf572ad1535cd43bff94cb44d5b30