[Clang][AMDGPU] Fix early exit when finding hip dlls AMDGPUArchByHIP.cpp (#166238)

To find the greatest versioned `amdhip64_n.dll`, We iterate through
`SearchPaths` and the files within each path.

The `if (!DLLNames.empty())` check will return true if the first
`SearchPath` contains a dll - this will result in the break statement
executing and all other SearchPaths being skipped, potentially missing
out on a greater versioned dll.

Removing the check and break allows for all `SearchPaths` to get checked
and `DLLNames` to cover the complete set of dlls presents.

Also, the current `compareVersions` function was not removing the .dll
portion of the VerStr resulting in incorrect comparisons between VtA and
VtB. Updated the function to handle the case - test ouput is as follows
(ignore SearchPath and DLLName logging).

```
offload-arch.exe
SearchPath: C:\Users\rocm\harry\llvm-project\build\Debug\bin
SearchPath: C:\Windows\system32
SearchPath: C:\Windows
SearchPath: C:\Windows\system32
SearchPath: C:\Windows
SearchPath: C:\Windows\System32\Wbem
SearchPath: C:\Windows\System32\WindowsPowerShell\v1.0\
SearchPath: C:\Windows\System32\OpenSSH\
SearchPath: C:\Program Files\Git\cmd
SearchPath: C:\Program Files\CMake\bin
SearchPath: C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\
SearchPath: C:\Users\rocm\harry\.venv\Lib\site-packages\_rocm_sdk_core\bin
SearchPath: C:\Users\rocm\AppData\Local\Microsoft\WindowsApps
SearchPath:
DLLName: C:/Windows/system32/amdhip64_6.dll
DLLName: C:/Windows/system32/amdhip64_7.dll
DLLName: C:/Windows/system32/amdhip64_6.dll
DLLName: C:/Windows/system32/amdhip64_7.dll
DLLName: C:/Users/rocm/harry/.venv/Lib/site-packages/_rocm_sdk_core/bin/amdhip64_7.dll
HIP Library Path: C:\Windows\system32\amdhip64_7.dll
gfx1151

Author: harkgill-amd

clang/tools/offload-arch/AMDGPUArchByHIP.cpp

@@ -98,8 +98,16 @@ static std::vector<std::string> getSearchPaths() {
 // Custom comparison function for dll name
 static bool compareVersions(StringRef A, StringRef B) {
   auto ParseVersion = [](StringRef S) -> VersionTuple {
-    size_t Pos = S.find_last_of('_');
-    StringRef VerStr = (Pos == StringRef::npos) ? S : S.substr(Pos + 1);
+    StringRef Filename = sys::path::filename(S);
+    size_t Pos = Filename.find_last_of('_');
+    if (Pos == StringRef::npos)
+      return VersionTuple();
+
+    StringRef VerStr = Filename.substr(Pos + 1);
+    size_t DotPos = VerStr.find('.');
+    if (DotPos != StringRef::npos)
+      VerStr = VerStr.substr(0, DotPos);
+
     VersionTuple Vt;
     (void)Vt.tryParse(VerStr);
     return Vt;
@@ -135,8 +143,6 @@ static std::pair<std::string, bool> findNewestHIPDLL() {
           Filename.ends_with(HipDLLSuffix))
         DLLNames.push_back(sys::path::convert_to_slash(DirIt->path()));
     }
-    if (!DLLNames.empty())
-      break;
   }
 
   if (DLLNames.empty())