Adjust clang version checking to account for other non-vanilla clangs

We can no longer make the assumption that all non-vanilla clang versions
are Apple's clang or that all other non vanilla clangs will work with
the given arguments. There are times where additional tools might use non vanilla clang
and the presumed arguments here will break compilation on those
platforms.

We might want to consider adding tooling-specific optimazation functions
long term to fetch desired optimizations on a platform basis.

tools/targets.py

@@ -24,15 +24,15 @@ def using_clang(env):
     return "clang" in os.path.basename(env["CC"])
 
 
-def is_vanilla_clang(env):
+def is_clang_type(env, family_string):
     if not using_clang(env):
         return False
     try:
         version = subprocess.check_output([env.subst(env["CXX"]), "--version"]).strip().decode("utf-8")
     except (subprocess.CalledProcessError, OSError):
         print("Couldn't parse CXX environment variable to infer compiler version.")
         return False
-    return not version.startswith("Apple")
+    return version.startswith(family_string)
 
 
 # Main tool definition
@@ -125,10 +125,10 @@ def generate(env):
             else:
                 env.Append(CCFLAGS=["-g2"])
         else:
-            if using_clang(env) and not is_vanilla_clang(env):
+            if using_clang(env) and is_clang_type(env, "Apple"):
                 # Apple Clang, its linker doesn't like -s.
                 env.Append(LINKFLAGS=["-Wl,-S", "-Wl,-x", "-Wl,-dead_strip"])
-            else:
+            elif is_clang_type(env, "clang"):
                 env.Append(LINKFLAGS=["-s"])
 
         if env["optimize"] == "speed":