Test failure under FreeBSD 10.2

[dspinellis]

csmake test 5 fails with

  /usr/include/runetype.h:92: error: syntax error

[dspinellis]

Line 92 of runetype.h is

extern _Thread_local const _RuneLocale *_ThreadRuneLocale;

It seems that _Thread_local isn't being handled correctly.

[dspinellis]

CScout wrongly objects

/usr/include/runetype.h:92: error: at most one storage class can be specified

However, const is a storage class qualifier, not specifier.

[dspinellis]

It's actually the combination of _Thread_local with static. See #14.