Use empty blas_ldflags if no cxx is configured

Author: lucianopaz

pytensor/link/c/cmodule.py

@@ -2773,6 +2773,9 @@ def check_libs(
         else:
             raise RuntimeError(f"Supplied flags {flags} failed to compile")
 
+    # If no compiler is available we default to empty ldflags
+    if not config.cxx:
+        return ""
     _std_lib_dirs = std_lib_dirs()
     if len(_std_lib_dirs) > 0:
         rpath = _std_lib_dirs[0]