大佬，Linux下编译遇到坑了。请教

[ELEVENEV]

请问大佬一个问题，我在编译的时候遇到下面这样的报错，

Makefile:227: recipe for target '.depend' failed
make: *** [.depend] Error 1
/home/hong/Android/Sdk/ndk-bundle/toolchains/x86_64-4.9/prebuilt/linux-x86_64/bin/x86_64-linux-android-gcc -Wno-maybe-uninitialized -Wshadow -O3 -ffast-math -m64 -Wall -I. -I. --sysroot=/home/hong/Android/Sdk/ndk-bundle/platforms/android-21/arch-x86_64/ -Os -fpic -std=gnu99 -D_GNU_SOURCE -mpreferred-stack-boundary=5 -fPIC -fomit-frame-pointer -fno-tree-vectorize -c -o x264.o x264.c
x264.c:40:20: fatal error: signal.h: No such file or directory
#include <signal.h>
^
compilation terminated.
<builtin>: recipe for target 'x264.o' failed
make: *** [x264.o] Error 1
/home/hong/Android/Sdk/ndk-bundle/toolchains/x86_64-4.9/prebuilt/linux-x86_64/bin/x86_64-linux-android-gcc -Wno-maybe-uninitialized -Wshadow -O3 -ffast-math -m64 -Wall -I. -I. --sysroot=/home/hong/Android/Sdk/ndk-bundle/platforms/android-21/arch-x86_64/ -Os -fpic -std=gnu99 -D_GNU_SOURCE -mpreferred-stack-boundary=5 -fPIC -fomit-frame-pointer -fno-tree-vectorize -c -o x264.o x264.c
x264.c:40:20: fatal error: signal.h: No such file or directory
#include <signal.h>
^
compilation terminated.
<builtin>: recipe for target 'x264.o' failed
make: *** [x264.o] Error 1

我发现signal.h文件老版本的NDK是在
ndk-bundle/platforms/android-14/arch-arm/usr/include文件夹目录下

而现在最新版本的NDK signal.h文件是在
ndk-bundle-sysroot-usr-include 文件夹目录下，

哪在配置这个路径的时候SYSROOT=$NDK_HOME/platforms/$ANDROID_API/arch-x86_64 应该怎么写呀，还是按照原来的这样写吗。