fs: properly handle fd passed to truncate()

[charlanxcc]

Currently, fs.truncate() silently fails when a file descriptor
is passed as the first argument. This commit changes this
behavior to properly call fs.ftruncate().

PR-URL: #9161
Reviewed-By: Colin Ihrig [email protected]
Reviewed-By: Timothy J Fontaine [email protected]

[charlanxcc]

Fix for build issue in 64 bit freebsd.

There are two build fixes. The first is in OS::GetSharedLibraryAddresses(). In this method two automatic variables have the same name: result. I changed one of them to addr to resolve the issue.

The second one is in OS::GetCurrentThreadId(). In here, the code tried to cast pthread_t (64 bit) to int (32 bit), resulting in error. Proper fix should be return type change to long. But as workaround for now, I modified it to ((int) (int64) (void *) pthread_self()) only for freebsd.