Fixes the following build error:
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_post’
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_wait'
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_init’
.../toolchain-i386_pentium4_gcc-7.3.0_glibc/lib/gcc/i486-openwrt-linux-gnu/7.3.0/../../../../i486-openwrt-linux-gnu/bin/ld: ../lib/libcom_err.so: undefined reference to `sem_destroy’
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>