libgcc_s.so.1 must be installed for pthread_cancel to work

[Gabor Z. Papp]

* Ryan Arnold <ryan.arnold@gmail.com>:

| The compiler that GLIBC is compiled with may very likely be different
| than the compiler which provided the system's libgcc_s library at
| runtime.

| The error you get comes at runtime and the configure time check would
| be an incorrect solution for the problem you're seeing at runtime.

Thank you for clearing that.

Should not this noted somewhere in the README
(glibc/pthread requires libgcc_s at runtime)?