Problems with NVIDIA compiler (former PGI)

[GiovanniBussi]

This is to report on failures using NVIDIA compiler.

• As it was noticed already (PBC distance does not work with all compilers #524) there's a problem with PBC. I reported this to NVIDIA, they will fix it. Meanwhile, they recommended using -Mnoautoinline option
• After applying that, I found a number of errors in tests involving lapack. I checked better, and it looks like there's a problem with NVIDIA compilers and our internal lapack. I will try to investigate more on this, but meanwhile the solution is to link external lapack (on my machine: LIBS=-lnvf -lrt).
• There is then a double free or corruption error in basic/rt-make-exceptions, seems related to a test that tries to LOAD a not existing library (LOAD FILE=nonexist.cpp) and is expected to result in an exception. I will also double check this if there's some error in the code or possibly report it to NVIDIA as well.
• In addition to all these, there are a few remaining numerical errors that seem harmless (I will decrease the number of digits).

Overall, it should be possible to have a working plumed with NVC++ using these options:

./configure CXX=nvc++ CXXFLAGS="-O3 -Mnoautoinline" LIBS="-lnvf -lrt"