gnupg-2.2.12# ls -l /usr/lib/librt.so
lrwxrwxrwx 1 root root 30  1月 28  2013 /usr/lib/librt.so -> /lib/i386-linux-gnu/librt.so.1
gnupg-2.2.12# ls -l /lib/i386-linux-gnu/librt.so.1
lrwxrwxrwx 1 root root 13  1月 28  2013 /lib/i386-linux-gnu/librt.so.1 -> librt-2.15.so
gnupg-2.2.12# ls -l /lib/i386-linux-gnu/librt-2.15.so
-rw-r--r-- 1 root root 30684  8月  2  2013 /lib/i386-linux-gnu/librt-2.15.so
gnupg-2.2.12# cd agent
agent# gcc -v -I/usr/local/include -Wall -Wno-pointer-sign -Wpointer-arith -g -O2 -lrt -o gpg-protect-tool gpg_protect_tool-protect-tool.o gpg_protect_tool-protect.o gpg_protect_tool-cvt-openpgp.o ../common/libcommon.a -L/usr/local/lib -lgcrypt -lgpg-error -lassuan
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/i686-linux-gnu/4.6/lto-wrapper
Target: i686-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6 --enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --enable-objc-gc --enable-targets=all --disable-werror --with-arch-32=i686 --with-tune=generic --enable-checking=release --build=i686-linux-gnu --host=i686-linux-gnu --target=i686-linux-gnu
Thread model: posix
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
COMPILER_PATH=/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/:/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/i686-linux-gnu/4.6/:/usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/:/usr/lib/gcc/i686-linux-gnu/4.6/../../../../lib/:/lib/i386-linux-gnu/:/lib/../lib/:/usr/lib/i386-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/i686-linux-gnu/4.6/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-I' '/usr/local/include' '-Wall' '-Wno-pointer-sign' '-Wpointer-arith' '-g' '-O2' '-o' 'gpg-protect-tool' '-L/usr/local/lib' '-mtune=generic' '-march=i686'
 /usr/lib/gcc/i686-linux-gnu/4.6/collect2 --sysroot=/ --build-id --no-add-needed --as-needed --eh-frame-hdr -m elf_i386 --hash-style=gnu -dynamic-linker /lib/ld-linux.so.2 -z relro -o gpg-protect-tool /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crt1.o /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crti.o /usr/lib/gcc/i686-linux-gnu/4.6/crtbegin.o -L/usr/local/lib -L/usr/lib/gcc/i686-linux-gnu/4.6 -L/usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu -L/usr/lib/gcc/i686-linux-gnu/4.6/../../../../lib -L/lib/i386-linux-gnu -L/lib/../lib -L/usr/lib/i386-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/i686-linux-gnu/4.6/../../.. -lrt gpg_protect_tool-protect-tool.o gpg_protect_tool-protect.o gpg_protect_tool-cvt-openpgp.o ../common/libcommon.a -lgcrypt -lgpg-error -lassuan -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/gcc/i686-linux-gnu/4.6/crtend.o /usr/lib/gcc/i686-linux-gnu/4.6/../../../i386-linux-gnu/crtn.o
gpg_protect_tool-protect.o: In function `calibrate_get_time':
/root/gnupg-2.2.12/agent/protect.c:118: undefined reference to `clock_gettime'
collect2: ld returned 1 exit status
agent#