prevent OSS_SemWait abort for SIGUSR1/2
SIGUSR1/2 are no deadly signals and must not abort OSS_SemWait. This bug caused the z16_simp tool malfunction under Linux. z16_simp is a tool of the 13Z016-06 CANopen driver package.
I tested this bugfix under CentOS 7 (Kernel 3.10) 32-bit/64-bit with z16_simp tool and Vector CANalyzer. The bug may cause other problems in MDIS drivers if OSS semaphores and OSS signals are used together.