Adjust HIP_COMPILER_FLAGS to support <$:$<>:> and SHELL: tags (#933) (#956)

In ROCm 4.5.0 hip compile flags are coming in differently.  This has
caused some parsing issues for the HIP_COMPILER_FLAGS variable.  As an example

    ROCm 4.3.0: --offload-arch=gfx900
    ROCm 4.5.0: <$<COMPILE_LANGUAGE:CXX>:SHELL:--offload-arch=gfx900>

Using existing code...
    $<$<COMPILE_LANGUAGE:CXX>:SHELL:--offload-arch=gfx900>
Becomes...
    $<$<COMPILE_LANGUAGE:CXX>:SHELL:

There are two problems with that.
  1) The "<" is not balanced with a "> due to the regex consuming the ">"
  2) There is still a `SHELL:`  label.

This commit repairs both.  I took the regex parsing code from ROCmSoftwarePlatform/MIOpen/blame/develop/CMakeLists.txt
but improved it to support handling of target features like
<$<COMPILE_LANGUAGE:CXX>:SHELL:--offload-arch=gfx900:xxx+>
Co-authored-by: Paul Fultz II <pfultz2@yahoo.com>
Co-authored-by: Paul Fultz II <pfultz2@yahoo.com>

src/targets/gpu/CMakeLists.txt

@@ -287,8 +287,10 @@ endif()
 include(TargetFlags)
 target_flags(HIP_COMPILER_FLAGS hip::device)
 # Remove cuda arch flags
-string(REGEX REPLACE "--cuda-gpu-arch=[^ \t\r\n]+" "" HIP_COMPILER_FLAGS "${HIP_COMPILER_FLAGS}")
-string(REGEX REPLACE "--offload-arch=[^ \t\r\n]+" "" HIP_COMPILER_FLAGS "${HIP_COMPILER_FLAGS}")
+string(REGEX REPLACE --cuda-gpu-arch=[a-z0-9]+ "" HIP_COMPILER_FLAGS "${HIP_COMPILER_FLAGS}")
+string(REGEX REPLACE --offload-arch=[a-z0-9:+-]+ "" HIP_COMPILER_FLAGS "${HIP_COMPILER_FLAGS}")
+string(REPLACE "$<LINK_LANGUAGE:CXX>" "1" HIP_COMPILER_FLAGS "${HIP_COMPILER_FLAGS}")
+string(REPLACE "SHELL:" "" HIP_COMPILER_FLAGS "${HIP_COMPILER_FLAGS}")
 message(STATUS "Hip compiler flags: ${HIP_COMPILER_FLAGS}")
 target_compile_definitions(migraphx_gpu PRIVATE 
     "-DMIGRAPHX_HIP_COMPILER=${CMAKE_CXX_COMPILER}"