breakpad.bbclass: set includedir in CXXFLAGS

Previously this was only set in CFLAGS.
An build issue was discovered while convering in internal application
from Qt4 to Qt5. As a result of this, the required header files were
no longer found, until we also set CXXFLAGS.

Signed-off-by: Anders Darander <anders@chargestorm.se>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-oe/classes/breakpad.bbclass

@@ -5,6 +5,7 @@
 DEPENDS += "breakpad breakpad-native"
 
 CFLAGS += "-I${STAGING_DIR_TARGET}${includedir}/breakpad "
+CXXFLAGS += "-I${STAGING_DIR_TARGET}${includedir}/breakpad "
 
 BREAKPAD_BIN ?= ""