fix: include spirv platform in clang branch of run_hipcc.cmake

[pvelesko]

Summary

• run_hipcc.cmake checked only HIP_PLATFORM == "amd" to enter the clang compiler branch; chipStar sets HIP_PLATFORM=spirv, so it fell into the else (nvcc) branch
• For shared libraries the nvcc branch appends --shared -Xcompiler '-fPIC'; when clang receives the quoted ''-fPIC'' as a positional argument it fails: clang++: error: no such file or directory: ''-fPIC''
• Fix: extend the condition to also match spirv

Root cause

# before
if("${HIP_PLATFORM}" STREQUAL "amd")

# after
if("${HIP_PLATFORM}" STREQUAL "amd" OR "${HIP_PLATFORM}" STREQUAL "spirv")

Reproducer

Found while building SeisSol with chipStar. SeisSol's Device submodule uses hip_add_library(... SHARED) with HIP_SOURCE_PROPERTY_FORMAT set, which routes compilation through run_hipcc.cmake. A regression test is included in the companion chipStar PR.

Test plan

• Build a SHARED HIP library via hip_add_library() with HIP_SOURCE_PROPERTY_FORMAT on chipStar (HIP_PLATFORM=spirv) — should compile without -fPIC quoting errors
• Existing AMD (HIP_PLATFORM=amd) and CUDA (HIP_PLATFORM=nvidia) builds unaffected