Tcmalloc fixes

[graydon]

This improves our ability to do memory profiling .. a bit:

• adds a --disable-tcmalloc so that you can use memory profilers that hook malloc like heaptrack
• fixes --enable-tracy-memory-tracking which was broken
• adds a doc about using them
• adds support for measuring the heap dynamically when tcmalloc is turned on
• does so during wasm compilation and reports a new metric
• renames the old metric to be even more clear that it's wasm bytes not memory

[Copilot]

Pull request overview

Adds configurable tcmalloc support, repairs Tracy memory-tracking configuration, and introduces heap measurements for Soroban module-cache compilation.

Changes:

• Adds --disable-tcmalloc and Tracy memory-tracking build flags.
• Reports WASM and heap-byte metrics during module-cache rebuilds.
• Documents Tracy and Heaptrack profiling workflows.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
configure.ac	Adds allocator configuration and compatibility checks.
common.mk	Defines Tracy memory-tracking flags.
src/util/TcmallocConfig.h	Declares heap-usage query API.
src/util/TcmallocConfig.cpp	Queries tcmalloc heap usage.
src/ledger/SharedModuleCacheCompiler.h	Tracks compilation heap measurements.
src/ledger/SharedModuleCacheCompiler.cpp	Samples and logs heap changes.
src/ledger/SorobanMetrics.h	Declares renamed and new metrics.
src/ledger/SorobanMetrics.cpp	Registers module-cache byte metrics.
src/ledger/LedgerManagerImpl.cpp	Publishes rebuild measurements.
src/transactions/test/InvokeHostFunctionTests.cpp	Updates renamed metric references.
docs/metrics.md	Documents metric changes.
performance-eval/performance-eval.md	Adds memory-profiling guidance.
INSTALL.md	Moves Windows Tracy instructions.
Builds/VisualStudio/stellar-core.vcxproj	Adds new utility sources.
Builds/VisualStudio/stellar-core.vcxproj.filters	Categorizes new utility sources.