Cleanup & warning fixes under MinGW64

[svaningelgem]

• removal of whitespaces at the end of a line.
• indentation (little bit)

Fix for warnings under MinGW64:

• the socket (DWORD) was compare to -1, should be vs INVALID_SOCKET
• a few of the parameters of the pthread-wrapper weren't used, mark them as unused so there ain't no warnings.
• SIGPIPEHandler was not used, and as it was a static, it spawned a warning about an unused function
• return type for connectionHandlerThread was a NULL casted, should be a 0
• conversion from GetLastError to %d caused a warning. Now bring it first to a DWORD always to mitigate the warning.

[svaningelgem]

One "big" todo here would be to interpret the WSAGetLastError better as the values are quite different between POSIX & Windows systems.