CELFFLAGS and friends are abused in Application.mk

[yamt]

CELFFLAGS/CXXELFFLAGS/AELFFLAGS/LDELFFLAGS are for ELF modules.
they should not be used eg. when building FLAT model libapps.

[yamt]

my understanding is:

• if CONFIG_BUILD_KERNEL=y, CELFFLAGS should be used
• if CONFIG_BUILD_LOADABLE=n, CFLAGS should be used
• otherwise, we need to build twice, one with CELFFLAGS and another with CFLAGS