Fix incorrect initial value of __kmp_affinity_type.

[hbae]

Summary

Affinity initialization code expects __kmp_affinity_type has the value affinity_default by default, but the cleanup code does not properly set the value back to affinity_default.
This may introduce some issues when multiple roots are trying to initialize/uninitialize the runtime successively.

[jlpeyton]

LGTM

openmp/trunk/runtime/src/kmp_affinity.cpp

if (__kmp_affinity_masks != NULL) {
         KMP_CPU_FREE_ARRAY(__kmp_affinity_masks, __kmp_affinity_num_masks);
         __kmp_affinity_masks = NULL;
     }
     if (__kmp_affin_fullMask != NULL) {
         KMP_CPU_FREE(__kmp_affin_fullMask);
         __kmp_affin_fullMask = NULL;
     }
     __kmp_affinity_num_masks = 0;
+    __kmp_affinity_type = affinity_default;
 # if OMP_40_ENABLED
     __kmp_affinity_num_places = 0;
 # endif
     if (__kmp_affinity_proclist != NULL) {
         __kmp_free(__kmp_affinity_proclist);
         __kmp_affinity_proclist = NULL;
     }
     if( address2os != NULL ) {