[clang] [OFFLOAD] Introduce libdevice function declarations for future use for math OpenMP wrappers (PR #182215)

[Nick Sarnie via cfe-commits]

sarnex wrote:

@fineg74 We are seeing test failures after this change on the buildbot:

Example:

```
******************** TEST 'libomptarget :: spirv64-intel :: api/omp_env_vars.c' FAILED ********************
Exit Code: 1
Command Output (stdout):
--
# RUN: at line 1
/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./bin/clang -fopenmp    -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/offload/test -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/offload -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src  -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/offload -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib  -fopenmp-targets=spirv64-intel /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/offload/test/api/omp_env_vars.c -o /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/offload/test/spirv64-intel/api/Output/omp_env_vars.c.tmp
# executed command: /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./bin/clang -fopenmp -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/offload/test -I /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/offload -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -L /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/offload -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/openmp/runtime/src -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -Wl,-rpath,/home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/./lib -fopenmp-targets=spirv64-intel /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/llvm-project/offload/test/api/omp_env_vars.c -o /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/runtimes/runtimes-bins/offload/test/spirv64-intel/api/Output/omp_env_vars.c.tmp
# .---command stderr------------
# | In file included from <built-in>:1:
# | In file included from /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/openmp_wrappers/__clang_openmp_device_functions.h:65:
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/__clang_spirv_libdevice_declares.h:58:28: error: unknown type name 'bool'
# |    58 | _CLC_OVERLOAD _CLC_CONSTFN bool __spirv_IsNan(float);
# |       |                            ^
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/__clang_spirv_libdevice_declares.h:59:28: error: unknown type name 'bool'
# |    59 | _CLC_OVERLOAD _CLC_CONSTFN bool __spirv_IsNan(double);
# |       |                            ^
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/__clang_spirv_libdevice_declares.h:60:28: error: unknown type name 'bool'
# |    60 | _CLC_OVERLOAD _CLC_CONSTFN bool __spirv_IsInf(float);
# |       |                            ^
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/__clang_spirv_libdevice_declares.h:61:28: error: unknown type name 'bool'
# |    61 | _CLC_OVERLOAD _CLC_CONSTFN bool __spirv_IsInf(double);
# |       |                            ^
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/__clang_spirv_libdevice_declares.h:62:28: error: unknown type name 'bool'
# |    62 | _CLC_OVERLOAD _CLC_CONSTFN bool __spirv_IsFinite(float);
# |       |                            ^
# | /home/test-user/llvm-buildbot-worker/intel-sycl-gpu/build/lib/clang/23/include/__clang_spirv_libdevice_declares.h:63:28: error: unknown type name 'bool'
# |    63 | _CLC_OVERLOAD _CLC_CONSTFN bool __spirv_IsFinite(double);
# |       |                            ^
# | 6 errors generated.
# `-----------------------------
# error: command failed with exit status: 1
--
********************
```

https://github.com/llvm/llvm-project/pull/182215