criu/log.c:356:16: error: called object type 'int' is not a function or function pointer
        int __errno = errno;
                      ^~~~~
/root/android-ndk/toolchains/llvm/prebuilt/linux-x86_64//sysroot/usr/include/errno.h:43:24: note: expanded from macro 'errno'
                ~~~~~~~^
criu/log.c:391:2: error: called object type 'int' is not a function or function pointer
        errno =  __errno;
        ^~~~~
/root/android-ndk/toolchains/llvm/prebuilt/linux-x86_64//sysroot/usr/include/errno.h:43:24: note: expanded from macro 'errno'

in Android NDK's errno.h:

42: int* __errno(void) __attribute_const__;
43: #define errno (*__errno())

so rename __errno to _errno to pass build

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>
Signed-off-by: Andrei Vagin <avagin@gmail.com>