[OpenMP] Fix GCC build issues and restore "Additional APIs used by th…

…e MSVC compiler for loop collapse (rectangular and non-rectangular loops)"

Fixes a GCC build issue (an instance of unallowed typename keyword) and reworks memory allocation
to avoid the use of C++ library based primitives ) in and restores the earlier commit https://reviews.llvm.org/D148393

Differential Revision: https://reviews.llvm.org/D149010

openmp/runtime/src/CMakeLists.txt

@@ -88,6 +88,7 @@ else()
     kmp_dispatch.cpp
     kmp_lock.cpp
     kmp_sched.cpp
+    kmp_collapse.cpp
   )
   if(WIN32)
     # Windows specific files

openmp/runtime/src/dllexports

@@ -401,6 +401,9 @@ kmpc_set_disp_num_buffers                   267
         __kmpc_sections_init                289
         __kmpc_next_section                 290
         __kmpc_end_sections                 291
+        __kmpc_process_loop_nest_rectang    293
+        __kmpc_calc_original_ivs_rectang    295
+        __kmpc_for_collapsed_init           296
 %endif
 
 # User API entry points that have both lower- and upper- case versions for Fortran.