This patch updates the atomic support for TS18508, namely:
– The atomic intrinsics now take a STAT= argument
– Add the new atomics atomic_{add,and,or,xor} and their fetch variants 
atomic_fetch_{add,and,or,xor} – and compare and swap (atomic_cas)

In addition, the previous implementation (for -fcoarray=single) used 
simple assignments; the patch changes those to using real atomic 
operations, which makes the atomic operations thread safe.

Build and regtested on x86-64-gnu-linux.
OK for the trunk?


As next step, library calls have to be added for -fcoarray=lib. For 
coarrays, I also a have still on my to do list: Adding a type-conversion 
test case for -fcorray=lib; implementing in the library the support for 
vector subscripts; and fixing an issue with nonallocatable polymorphic 
dummy coarrays and select type.
For full F2008 support, the following is needed as well: locking and 
critical blocks – and allocatable/pointer components of derived types. 
For TS18508 much more is needed, in particular co_reduce/co_broadcast 
and team support.

Tobias