1. Make can't exit while compilation error occurs in subdir for plugins building.
2. If build ppp with newer kernel (3.10.10), it will pick 'if_pppox.h' from sysroot-dir and
'if_pppol2tp.h' from its own source dir, this cause below build errors:
bitbake_build/tmp/sysroots/intel-x86-64/usr/include/linux/if_pppox.h:84:26:
error: field 'pppol2tp' has incomplete type
struct pppol2tpin6_addr pppol2tp;
^
bitbake_build/tmp/sysroots/intel-x86-64/usr/include/linux/if_pppox.h:99:28:
error: field 'pppol2tp' has incomplete type
struct pppol2tpv3in6_addr pppol2tp;
^
The 'sysroot-dir/if_pppox.h' enabled ipv6 support but the 'source-dir/if_pppol2tp.h' lost
related structure definitions, we should use both header files from sysroots to fix this
build failure.
Signed-off-by: Lu Chong <Chong.Lu@windriver.com> Signed-off-by: Saul Wold <sgw@linux.intel.com>