Configure failure detecting logical kinds for MPI

**Describe the bug**

Running configure with --enable-fortran and --enable-parallel fails like this:

configure: error: Failed to find Fortran KIND of LOGICAL in MPI

**Expected behavior**

Configure should work.

**Platform (please complete the following information)**
- HDF5 version: 1.14.4.3
- OS and version: RHEL7 Linux
- Compiler and version: gnu 9.2.0
- Build system (e.g. CMake, Autotools) and version: autotools
- Any configure options you specified: --enable-fortran --enable-parallel
- MPI library and version (parallel HDF5): mpich 4.2.2

**Additional context**

In the past we have passed the location of the MPI library by setting FCFLAGS. However it looks like the configure script is doing this:

saved_FCFLAGS=$FCFLAGS
check_Intel="`$FC -V 2>&1 |grep '^Intel'`"
if test X != "X$check_Intel"; then
FCFLAGS="-warn error"
else
FCFLAGS=""
fi

This means that the FCFLAGS gets unset resulting in this compile line being executed:

configure:33247: gfortran -c conftest.f90 >&5

which fails as it cannot find the MPI module.