Turn off `clang::musttail` on i386

We found last week that Clang's support for `musttail` on 32-bit Linux does not
seem to work reliably, so let's disable it for now.

PiperOrigin-RevId: 528817403

src/google/protobuf/port_def.inc

@@ -324,7 +324,7 @@ static_assert(PROTOBUF_CPLUSPLUS_MIN(201402L), "Protobuf only supports C++14 and
 #endif
 #if __has_cpp_attribute(clang::musttail) && !defined(__arm__) &&      \
     !defined(_ARCH_PPC) && !defined(__wasm__) &&                      \
-    !(defined(_MSC_VER) && defined(_M_IX86)) &&                  \
+    !(defined(_MSC_VER) && defined(_M_IX86)) && !defined(__i386__) && \
     !(defined(__NDK_MAJOR__) && __NDK_MAJOR <= 24)
 #  ifndef PROTO2_OPENSOURCE
 // Compilation fails on ARM32: b/195943306