[ASan][AMDGPU] Retry HSA resolution after late HIP load

[sa-faizal]

ASan can initialize before applications that dlopen() HIP have loaded ROCr. The initial RTLD_NEXT lookups then leave the AMDGPU HSA callback table incomplete.

After the real hsa_init() succeeds, retry the idempotent HSA symbol lookup before registering the shutdown callback. If resolution still fails, reset the registration guard and return instead of calling through a null function pointer.

Add a regression that starts ASan first, dlopens libamdhip64.so.7, and calls hipInit.

Validation:

• clang_rt.asan-dynamic-x86_64 rebuilt successfully.
• The regression reproduces the null-PC abort with the old runtime.
• The rebuilt runtime prints hipInit succeeded.
• The matching ctypes/GPU probe returns hipInit_status 0.
• clang-format --dry-run --Werror and git diff --check pass.