Android NDK: necessary Makefile changes

1, do not hardcode libnl's cflags
    when cross compile CRIU, libnl's header file should not point to host.

2, remove link to rt
    Android NDK doesn't have library rt, and CRIU is not really need it,
    so disable it to pass link

Cc: Chen Hu <hu1.chen@intel.com>
Signed-off-by: Zhang Ning <ning.a.zhang@intel.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>

criu/Makefile

@@ -26,7 +26,7 @@ ccflags-y		+= -iquote include
 ccflags-y		+= -iquote images
 ccflags-y		+= -iquote $(ARCH_DIR)/include
 ccflags-y		+= -iquote .
-ccflags-y		+= -I/usr/include/libnl3
+ccflags-y		+= $(shell pkg-config --cflags libnl-3.0)
 ccflags-y		+= $(COMPEL_UAPI_INCLUDES)
 ccflags-y		+= $(CONFIG-DEFINES)
 

criu/Makefile.packages

@@ -32,7 +32,7 @@ REQ-DEB-PKG-NAMES	+= python-future
 REQ-RPM-PKG-TEST-NAMES	+= $(PYTHON)-pyyaml
 endif
 
-export LIBS		+= -lrt -lpthread -lprotobuf-c -ldl -lnl-3 -lsoccr -Lsoccr/ -lnet
+export LIBS		+= -lprotobuf-c -ldl -lnl-3 -lsoccr -Lsoccr/ -lnet
 
 check-packages-failed:
 	$(warning Can not find some of the required libraries)