CXXFLAGS to sub-makes.
The bad passing also causes bsd.dep.mk's logic to selectively pull only some
flags from C[XX]FLAGS to not apply which can be seen with '-L' being passed to
mkdep when using an external compiler.
.if defined(X_COMPILER_TYPE) && ${X_COMPILER_TYPE} == gcc
XCFLAGS+= -isystem ${WORLDTMP}/usr/include -L${WORLDTMP}/usr/lib
XCXXFLAGS+= -I${WORLDTMP}/usr/include/c++/v1 -std=gnu++11 -L${WORLDTMP}/../lib/libc++
+# XXX: DEPFLAGS is a workaround for not properly passing CXXFLAGS to sub-makes
+# due to CXX="${XCXX} ${XCXXFLAGS}". bsd.dep.mk does use CXXFLAGS when
+# building C++ files so this can come out if passing CXXFLAGS down is fixed.
DEPFLAGS+= -I${WORLDTMP}/usr/include/c++/v1
.else
TARGET_ABI?= unknown