mpit: Fix MPI_T_pvar_get_index

[nysal]

@hjelmn Please take a look.

MPI_T_pvar_get_index was returning an incorrect index. The index
was never set correctly while registering the performance variables.
Additionally fix a missing case in the mca_base_var_type_t to MPI
datatype conversion. This type is currently used for control variables
registered by mxm, fca and hcoll components.

This fixes the mpich test - http://git.mpich.org/mpich.git/blob/HEAD:/test/mpi/mpi_t/getindex.c
You might need a few changes to run the test:

--- getindex.c	2016-11-15 17:20:56.089095214 +0530
+++ getindex_new.c	2016-11-15 17:23:15.891400761 +0530
@@ -31,7 +31,8 @@
         fprintf(stdout, "%d MPI Control Variables\n", num_cvar);
     for (i = 0; i < num_cvar; i++) {
         namelen = sizeof(name);
-        MPI_T_cvar_get_info(i, name, &namelen, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
+        errno = MPI_T_cvar_get_info(i, name, &namelen, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
+        if(errno != MPI_SUCCESS) continue;
         if (namelen <= 128) {
             errno = MPI_T_cvar_get_index(name, &cvar_index);
             if (errno != MPI_SUCCESS || cvar_index != i)
@@ -52,8 +53,9 @@
 
     for (i = 0; i < num_pvar; i++) {
         namelen = sizeof(name);
-        MPI_T_pvar_get_info(i, name, &namelen, NULL, &pvar_class, NULL, NULL, NULL,
+        errno = MPI_T_pvar_get_info(i, name, &namelen, NULL, &pvar_class, NULL, NULL, NULL,
                             NULL, NULL, NULL, NULL, NULL);
+        if(errno != MPI_SUCCESS) continue;
         if (namelen <= 128) {
             errno = MPI_T_pvar_get_index(name, pvar_class, &pvar_index);
             if (errno != MPI_SUCCESS || pvar_index != i)
@@ -74,7 +76,8 @@
         fprintf(stdout, "%d MPI_T categories\n", num_cat);
     for (i = 0; i < num_cat; i++) {
         namelen = sizeof(name);
-        MPI_T_category_get_info(i, name, &namelen, NULL, NULL, NULL, NULL, NULL);
+        errno = MPI_T_category_get_info(i, name, &namelen, NULL, NULL, NULL, NULL, NULL);
+        if(errno != MPI_SUCCESS) continue;
         if (namelen <= 128) {
             errno = MPI_T_category_get_index(name, &cat_index);
             if (errno != MPI_SUCCESS || cat_index != i)

[nysal]

@jsquyres Could you check in the weekly meeting if Nathan or someone else can review this PR?

[jsquyres]

@hjelmn Looked at this quickly while on the webex and thought it was correct. He will check deeper shortly.

[hjelmn]

Please PR to any affected version. Probably 2.0.x and 2.x.