lisa._kmod: Warn about non ideal toolchain in more situations

FIX

Warn about toolchain mismatching what the kernel was compiled with in
absolute terms.

lisa/_kmod.py

@@ -1465,6 +1465,9 @@ def _resolve_toolchain(cls, abi, build_conf, target=None):
         def priority_to(cc):
             return lambda _cc: 0 if cc in _cc.name else 1
 
+        def is_perfect(cc):
+            return cc_priority(cc) == 0
+
         cc_priority = priority_to('clang')
 
         if target:
@@ -1505,6 +1508,9 @@ def cc_priority(cc):
                                 return version_key(version)
                         else:
                             return (3,)
+
+                    def is_perfect(cc):
+                        return cc_priority(cc) == (0, 0)
             else:
                 try:
                     proc_version = target.read_value('/proc/version')
@@ -1682,7 +1688,7 @@ def version_cmd(cc, cross_compile):
             raise ValueError(f'Could not detect which CROSS_COMPILE value to use')
 
         ideal_cc, _ = ccs[0]
-        if str(cc) != str(ideal_cc):
+        if str(cc) != str(ideal_cc) or not is_perfect(cc):
             logger.warning(f'Could not find ideal CC={ideal_cc} but found CC={cc} instead. Results may vary from working fine to crashing the kernel')
 
         return (cc, cross_compile, cc_key)