libcamera: fix c++ flags and failed buildpaths QA check

Building libcamera from the latest version of meta-or fails
the buildpaths qa check with a number of generated binaries.

Looking into the logs, it seemed that the -f*-prefix-map
flags were present to gcc invocations, but the used flags
were quite off for g++ invocations. It seems that using
the cpp_args meson option overwrites (at least most of)
the CXXFLAGS set by Yocto, including the -f*-prefix-map
flags.

To avoid this, append the extra compile flag to the
CXXFLAGS variable instead of using meson's cpp_args option.

Signed-off-by: Gyorgy Sarvari <[email protected]>

Author: OldManYellsAtCloud

dynamic-layers/multimedia-layer/recipes-multimedia/libcamera/libcamera_%.bbappend

@@ -1,2 +1,3 @@
-PACKAGECONFIG[raspberrypi] = "-Dpipelines=rpi/vc4 -Dipas=rpi/vc4 -Dcpp_args=-Wno-unaligned-access"
+PACKAGECONFIG[raspberrypi] = "-Dpipelines=rpi/vc4 -Dipas=rpi/vc4"
 PACKAGECONFIG:append:rpi = " raspberrypi"
+CXXFLAGS:append:rpi = " -Wno-unaligned-access "