gromacs: fix fftw and update cmake dependencies (#17226)

* gromacs: fix fftw dependency

Only depend on fftw+mpi when gromacs is built with mpi,
and depend on fftw~mpi otherwise.

* gromacs: fix cmake dependency

master branch depends on cmake 3.11 (as specified in CMakeLists.txt
cmake dependency is also bumped to 3.11 when fj compilers are used
in order to fix OpenMP detection.

var/spack/repos/builtin/packages/gromacs/package.py

@@ -73,9 +73,12 @@ class Gromacs(CMakePackage):
     depends_on('mpi', when='+mpi')
     depends_on('plumed+mpi', when='+plumed+mpi')
     depends_on('plumed~mpi', when='+plumed~mpi')
-    depends_on('fftw')
+    depends_on('fftw+mpi', when='+mpi')
+    depends_on('fftw~mpi', when='~mpi')
     depends_on('cmake@2.8.8:3.99.99', type='build')
     depends_on('cmake@3.4.3:3.99.99', type='build', when='@2018:')
+    depends_on('cmake@3.13.0:3.99.99', type='build', when='@master')
+    depends_on('cmake@3.13.0:3.99.99', type='build', when='%fj')
     depends_on('cuda', when='+cuda')
 
     # TODO: openmpi constraint; remove when concretizer is fixed