package/edid-decode: use TARGET_CONFIGURE_OPTS

package/edid-decode: use TARGET_CONFIGURE_OPTS

Do not use CXX to set the "$(TARGET_CXX) $(TARGET_CXXFLAGS)
$(TARGET_LDFLAGS)" variables and instead use TARGET_CONFIGURE_OPTS to
pass variables using the "standard" variables.

LDFLAGS is supported since
https://git.linuxtv.org/edid-decode.git/commit/?id=0a454bcbba5e172c64236811ed98c161689372f1

CFLAGS is supported since
https://git.linuxtv.org/edid-decode.git/commit/?id=b202b675e38578b33494fc45c2869917e66ba22d

edid-decode did not switch CFLAGS to CXXFLAGS in
https://git.linuxtv.org/edid-decode.git/commit/Makefile?id=e00579c128ced87a69df29a01caaaf0cd4a4c8cc
so use CFLAGS to pass TARGET_CXXFLAGS

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>