Fix compile error when using glibc in openwrt

[DongCai008]

[ 66%] Built target uhttpd make[6]: Entering directory '/home/xxx/openwrt-compile/openwrt/build_dir/target-x86_64_glibc/libuhttpd-nossl/libuhttpd-2.0.3' make[6]: Leaving directory '/home/xxx/openwrt-compile/openwrt/build_dir/target-x86_64_glibc/libuhttpd-nossl/libuhttpd-2.0.3' make[6]: Entering directory '/home/xxx/openwrt-compile/openwrt/build_dir/target-x86_64_glibc/libuhttpd-nossl/libuhttpd-2.0.3' [ 75%] Linking C executable helloworld /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to sinh' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference toceil' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to atan2' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference totanh' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to atanh' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference tocosh' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to fmod' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference toacosh' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to acos' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference tosin' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to atan' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference toasin' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to exp' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference totan' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to cos' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference tolog' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to pow' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference tolog10' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to sqrt' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference toasinh' /home/xxx/openwrt-compile/openwrt/staging_dir/target-x86_64_glibc/usr/lib/liblua.so: undefined reference to `floor'