Update CFLAGS to add Wall, Werror, Wextra everywhere
Update CFLAGS to add Wall, Werror, Wextra everywhere

BZ: 129048

Some Makefiles of the PFW projects are missing the regular CFLAGS
-Wall, -Werror and -Wextra.

This patch aims to update the CLFAGS of these Makefiles. Some source
code had to be updated because warnings are now considered as errors.

Change-Id: Icc91f7bdc649118f822411d9b4693776a84037e9
Signed-off-by: Frédéric Boisnard <9b2e931efdb868e9d011911aec6f661a672fd504@intel.com>

android-ia/vendor_intel_hardware_audiocomms_parameter-framework_plugins_fs,android-ia/vendor_intel_hardware_audiocomms_parameter-framework_plugins_fs,01org/parameter-framework-plugins-filesystem,clero/parameter-framework-plugins-filesystem,clero/parameter-framework-plugins-filesystem,01org/parameter-framework-plugins-filesystem