[llvm] [Offload][OMPX] Add the runtime support for multi-dim grid and block (PR #118042)

[Jan Patrick Lehr via llvm-commits]

jplehr wrote:

I see these two failures on a local test run
``` 
  libomptarget :: x86_64-unknown-linux-gnu :: api/omp_env_vars.c
  libomptarget :: x86_64-unknown-linux-gnu-LTO :: api/omp_env_vars.c
```

The error message is
```
# .---command stderr------------
# | /work/janplehr/git/llvm-project/offload/test/api/omp_env_vars.c:8:12: error: CHECK: expected string not found in input
# |  // CHECK: Launching kernel [[KERNEL:.+_main_.+]] with [1,1,1] blocks and [1,1,1] threads
# |            ^
...
# | Input was:
# | <<<<<<
# |            1: "PluginInterface" device 0 info: Launching kernel __omp_offloading_fd00_61c4b8b_main_l9 with [0,1,1] blocks and [0,1,1] threads in Generic mode 
# | check:8'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
# | check:8'1                                                           ?                                                                                          possible intended match
# | >>>>>>
```

https://github.com/llvm/llvm-project/pull/118042