contrib: remove librt from release deps

Author: fanquake

contrib/devtools/symbol-check.py

@@ -98,7 +98,6 @@
 'libc.so.6', # C library
 'libpthread.so.0', # threading
 'libm.so.6', # math library
-'librt.so.1', # real-time (clock)
 'libatomic.so.1',
 'ld-linux-x86-64.so.2', # 64-bit dynamic linker
 'ld-linux.so.2', # 32-bit dynamic linker