[CodeLayout] Do not rebuild chains with -apply-ext-tsp-for-size

[ellishg]

#109711 disables buildCFGChains() when -apply-ext-tsp-for-size is used to improve codesize. Tail merging can change the layout and normally requires buildCFGChains() to be called again, but we want to prevent this when optimizing for codesize. We saw slight size improvement on large binaries with this change. If -apply-ext-tsp-for-size is not used, this should be a NFC.

[kyulee-com]

LGTM

[llvm-ci]

LLVM Buildbot has detected a new failure on builder llvm-x86_64-debian-dylib running on gribozavr4 while building llvm at step 7 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/13007

Here is the relevant piece of the build log for the reference

Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM :: ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
RUN: at line 1: /b/1/llvm-x86_64-debian-dylib/build/bin/lli -jit-kind=orc-lazy -compile-threads=2 -thread-entry hello /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
+ /b/1/llvm-x86_64-debian-dylib/build/bin/lli -jit-kind=orc-lazy -compile-threads=2 -thread-entry hello /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.	Program arguments: /b/1/llvm-x86_64-debian-dylib/build/bin/lli -jit-kind=orc-lazy -compile-threads=2 -thread-entry hello /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll
 #0 0x00007fd4a29a8b07 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/b/1/llvm-x86_64-debian-dylib/build/lib/libLLVM.so.20.0git+0xf3ab07)
 #1 0x00007fd4a29a65be llvm::sys::RunSignalHandlers() (/b/1/llvm-x86_64-debian-dylib/build/lib/libLLVM.so.20.0git+0xf385be)
 #2 0x00007fd4a29a91df SignalHandler(int) Signals.cpp:0:0
 #3 0x00007fd4a1a58140 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x13140)
 #4 0x00007fd4a5058a69 llvm::orc::JITDylib::clear() (/b/1/llvm-x86_64-debian-dylib/build/lib/libLLVM.so.20.0git+0x35eaa69)
 #5 0x00007fd4a5066c57 llvm::orc::ExecutionSession::removeJITDylibs(std::vector<llvm::IntrusiveRefCntPtr<llvm::orc::JITDylib>, std::allocator<llvm::IntrusiveRefCntPtr<llvm::orc::JITDylib>>>) (/b/1/llvm-x86_64-debian-dylib/build/lib/libLLVM.so.20.0git+0x35f8c57)
 #6 0x00007fd4a50667d2 llvm::orc::ExecutionSession::endSession() (/b/1/llvm-x86_64-debian-dylib/build/lib/libLLVM.so.20.0git+0x35f87d2)
 #7 0x00007fd4a50ea326 llvm::orc::LLJIT::~LLJIT() (/b/1/llvm-x86_64-debian-dylib/build/lib/libLLVM.so.20.0git+0x367c326)
 #8 0x00007fd4a50ef531 llvm::orc::LLLazyJIT::~LLLazyJIT() crtstuff.c:0:0
 #9 0x0000000000415626 runOrcJIT(char const*) (/b/1/llvm-x86_64-debian-dylib/build/bin/lli+0x415626)
#10 0x000000000040fe49 main (/b/1/llvm-x86_64-debian-dylib/build/bin/lli+0x40fe49)
#11 0x00007fd4a1569d7a __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x23d7a)
#12 0x000000000040e9aa _start (/b/1/llvm-x86_64-debian-dylib/build/bin/lli+0x40e9aa)
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/llvm/test/ExecutionEngine/OrcLazy/multiple-compile-threads-basic.ll

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