Set TextFormat default recursion limit to 100

[gladiator9797]

Summary

The TextFormat::Parser constructor initializes recursion_limit_ to std::numeric_limits<int>::max() (2,147,483,647) at text_format.cc:1803. This is inconsistent with:

• Binary format parser: default 100 (CodedInputStream::default_recursion_limit_)
• JSON parser: default 64-100
• UPB binary decoder: default 100 (kUpb_WireFormat_DefaultDepthLimit)

A textproto with ~5,000-10,000 nested messages overflows the C stack before the recursion check ever triggers, causing SIGSEGV.

Fix

Change the default from std::numeric_limits<int>::max() to 100, matching CodedInputStream::default_recursion_limit_. Users who need a different limit can still call SetRecursionLimit().

Reproducer

// Parse deeply nested textproto
std::string textproto;
for (int i = 0; i < 10000; i++) textproto += "nested_type { ";
textproto += "name: \"x\"";
for (int i = 0; i < 10000; i++) textproto += " }";

DescriptorProto msg;
TextFormat::ParseFromString(textproto, &msg);  // SIGSEGV

$ ulimit -s 8192 && ./test
EXIT=139  (SIGSEGV - stack overflow)

Test plan

• Verified crash with default limit (exit 139)
• SetRecursionLimit() API still works for custom limits
• Existing protobuf test suite passes