protobuf: cleanup

remove dead code and patches

identified in conan-io#21163 and conan-io#21146

recipes/protobuf/all/conanfile.py

@@ -48,18 +48,12 @@ def _is_clang_cl(self):
     def _is_clang_x86(self):
         return self.settings.compiler == "clang" and self.settings.arch == "x86"
 
-    @property
-    def _can_disable_rtti(self):
-        return Version(self.version) >= "3.15.4"
-
     def export_sources(self):
         export_conandata_patches(self)
 
     def config_options(self):
         if self.settings.os == "Windows":
             del self.options.fPIC
-        if not self._can_disable_rtti:
-            del self.options.with_rtti
 
     def configure(self):
         if self.options.shared:
@@ -79,7 +73,7 @@ def validate(self):
         check_min_vs(self, "190")
 
         if self.settings.compiler == "clang":
-            if Version(self.version) >= "3.15.4" and Version(self.settings.compiler.version) < "4":
+            if Version(self.settings.compiler.version) < "4":
                 raise ConanInvalidConfiguration(f"{self.ref} doesn't support clang < 4")
 
     def source(self):
@@ -97,10 +91,8 @@ def generate(self):
         tc.cache_variables["protobuf_BUILD_PROTOC_BINARIES"] = self.settings.os != "tvOS"
         if not self.options.debug_suffix:
             tc.cache_variables["protobuf_DEBUG_POSTFIX"] = ""
-        if Version(self.version) >= "3.14.0":
-            tc.cache_variables["protobuf_BUILD_LIBPROTOC"] = self.settings.os != "tvOS"
-        if self._can_disable_rtti:
-            tc.cache_variables["protobuf_DISABLE_RTTI"] = not self.options.with_rtti
+        tc.cache_variables["protobuf_BUILD_LIBPROTOC"] = self.settings.os != "tvOS"
+        tc.cache_variables["protobuf_DISABLE_RTTI"] = not self.options.with_rtti
         if is_msvc(self) or self._is_clang_cl:
             runtime = msvc_runtime_flag(self)
             if not runtime: