**Describe the bug** linux环境下,在build/linux/目录下,执行./configure,当存在“CFLAGS”环境变量时,会干扰大小端的测试,导致configure失败,终端输出“endian test failed” **To Reproduce** 设置环境变量CFLAGS: export CFLAGS="-march=native -O2 -ftree-loop-vectorize -pipe -fstack-protector-strong -fstack-clash-protection -fno-plt -fexceptions -fasynchronous-unwind-tables -flto -grecord-gcc-switches" 执行./configure 输出:endian test failed **Expected behavior** 在编译发布版本时,使用上述CFLAGS以获得更好的优化是很常见的,configure不应当因此而失败。 **Screenshots**  **Desktop (please complete the following information):** - OS: Arch Linux - Compiler: gcc (GCC) 10.2.0 - yasm: 1.3.0 **个人解决方案:** 见附件 [fix-endian-test-failed-with-cflags.patch.txt](https://github.com/pkuvcl/davs2/files/5936728/fix-endian-test-failed-with-cflags.patch.txt)