BUG: compiler-specific INTELMPI not always found (closes #830)

- tie the MPI rules to the base compiler type *without* its version.
  Eg, linux64Gcc (which exists) instead of linux64Gcc81

src/Pstream/mpi/Make/options

 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
-sinclude $(RULES)/mplib$(WM_MPLIB)
+sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
 EXE_INC  = $(PFLAGS) $(PINC) $(c++LESSWARN)
 LIB_LIBS = $(PLIBS)

src/parallel/decompose/ptscotchDecomp/Make/options

 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
-sinclude $(RULES)/mplib$(WM_MPLIB)
+sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
 EXE_INC = \
     $(PFLAGS) $(PINC) \

src/parallel/decompose/scotchDecomp/Make/options

@@ -3,7 +3,7 @@
  * This is purely to avoid scotch.h including mpicxx.h, which causes problems.
  */
 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
-sinclude $(RULES)/mplib$(WM_MPLIB)
+sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
 EXE_INC = \
     $(PFLAGS) $(PINC) \

src/renumber/zoltanRenumber/Make/options

 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
-sinclude $(RULES)/mplib$(WM_MPLIB)
+sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
 EXE_INC = \
     /* -DFULLDEBUG -g -O0 */ \

wmake/rules/General/ADIOS

@@ -2,7 +2,7 @@
 # ADIOS includes/libraries
 
 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
-sinclude $(RULES)/mplib$(WM_MPLIB)
+sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
 # Obtain compile/link flags via adios_config
 ADIOS_INC  := $(shell $(ADIOS_ARCH_PATH)/bin/adios_config -c)

wmake/rules/General/ADIOS2

@@ -2,7 +2,7 @@
 # ADIOS2 includes/libraries
 
 sinclude $(GENERAL_RULES)/mplib$(WM_MPLIB)
-sinclude $(RULES)/mplib$(WM_MPLIB)
+sinclude $(DEFAULT_RULES)/mplib$(WM_MPLIB)
 
 # Obtain prefix and library information via adios2-config
 ADIOS_PREFIX := $(shell $(ADIOS2_ARCH_PATH)/bin/adios2-config --prefix)