Honor user-defined configopts in LLVM easyblock

Author: Flamefire

easybuild/easyblocks/l/llvm.py

@@ -1032,7 +1032,10 @@ def add_cmake_opts(self):
         """Add LLVM-specific CMake options."""
         base_opts = self._cfgopts.copy()
         for k, v in self._cmakeopts.items():
-            base_opts.append('-D%s=%s' % (k, v))
+            opt_start = f'-D{k}='
+            # Don't overwrite e.g. user settings
+            if not any(opt.startswith(opt_start) for opt in base_opts):
+                base_opts.append(f'-D{k}={v}')
         self.cfg['configopts'] = ' '.join(base_opts)
 
     def configure_step2(self):