Add AddressSanitizer support for clang-cl builds

Select the clang-cl-asan CMake preset (RelWithDebInfo, clang-cl,
ADDRESS_SANITIZER=ON) to instrument first-party code with AddressSanitizer.
The wiring lives in cmake/AddressSanitizer.cmake; SANITIZERS.md tells how to
add the clang-cl tools, build, and read the report.

Details:
- Add the clang-cl-asan preset so the asan build is one selection in Visual
  Studio, and a base for a CMakeUserPresets.json to inherit.
- Instrument first-party code only; the vendored libraries keep default flags.
- Use the release CRT and disable MSVC-STL container annotations, so
  instrumented and un-instrumented TUs stay compatible.
- Pass /bigobj to the TUs asan inflates past the COFF section cap.
- Link the asan runtime for clang-cl (lld-link does not infer it).
- Stub Bink into the exe: retail binkw32.dll cannot load in an asan process
  (its image base is the 32-bit shadow), so compile no-op exports instead.
- Route the asan report to gamedir/asan.report.<pid>, since every app is a
  WIN32 GUI app with no console to receive the default stderr report.
- Opt functions with 32-bit inline __asm out of instrumentation with
  cmake/asan-ignorelist.txt, one function at a time (asan reserves a register
  the asm needs). The rest of each translation unit stays instrumented.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cmake/AddressSanitizer.cmake

@@ -0,0 +1,50 @@
+# AddressSanitizer wiring, kept in one place. Include this early: it declares
+# the option and the _asan generator expression that the CRT selection in the
+# root CMakeLists depends on. The two functions are ordered hook points the
+# root calls at the right moments:
+#   ja2_asan_instrument_first_party() — after the vendored add_subdirectory()s
+#     (they must keep default flags), before our own targets are defined.
+#   ja2_asan_link_binkw32_stub(<exe>) — per executable, links the Bink stubs in.
+
+option(ADDRESS_SANITIZER "Enable AddressSanitizer for Debug and RelWithDebInfo" OFF)
+
+# asan only on the debuggable configs, shared by the flag and the CRT choice
+set(_asan "$<AND:$<BOOL:${ADDRESS_SANITIZER}>,$<OR:$<CONFIG:Debug>,$<CONFIG:RelWithDebInfo>>>")
+
+if(ADDRESS_SANITIZER)
+  message(STATUS "AddressSanitizer ENABLED for Debug and RelWithDebInfo (first-party code only)")
+  message(STATUS "  Bink stubbed into the exe; no binkw32.dll import, so the asan exe runs from gamedir untouched")
+  # keep MSVC-STL container annotations uniform across un-instrumented TUs
+  add_compile_definitions("$<${_asan}:_DISABLE_STL_ANNOTATION>")
+  # retail binkw32.dll cannot load in an asan process (image base 0x30000000 is
+  # the 32-bit shadow). __RADINEXE__ makes bink.h declare the Bink functions as
+  # in-exe calls instead of dllimports (sgp/RAD.H), so ja2_asan_link_binkw32_stub
+  # can satisfy them from sgp/binkw32_stub.c and the exe imports no binkw32.dll.
+  # Configure-time, not per-config: it must stay in lockstep with dropping the
+  # binkw32 import library from the link (see root CMakeLists).
+  add_compile_definitions(__RADINEXE__)
+endif()
+
+function(ja2_asan_instrument_first_party)
+  # instrument first-party code; /bigobj for the TUs asan inflates past the COFF
+  # section cap (LanguageStrings.cpp). The ignorelist opts individual functions
+  # with 32-bit inline __asm out of instrumentation (see cmake/asan-ignorelist.txt).
+  # Empty when the option is off.
+  add_compile_options(
+    "$<${_asan}:-fsanitize=address;-fsanitize-ignorelist=${CMAKE_SOURCE_DIR}/cmake/asan-ignorelist.txt;/bigobj>")
+
+  # clang-cl/lld-link do not infer the asan runtime; /WHOLEARCHIVE is invalid for llvm-lib
+  if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    add_link_options(
+      "$<$<AND:${_asan},$<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>>:clang_rt.asan_dynamic-i386.lib;/WHOLEARCHIVE:clang_rt.asan_static_runtime_thunk-i386.lib>")
+  endif()
+endfunction()
+
+function(ja2_asan_link_binkw32_stub exe)
+  # Compile the no-op Bink exports into the exe. With __RADINEXE__ above the game
+  # calls them directly, so this replaces the binkw32.dll the retail import
+  # library would have pulled in.
+  if(ADDRESS_SANITIZER)
+    target_sources(${exe} PRIVATE "${CMAKE_SOURCE_DIR}/sgp/binkw32_stub.c")
+  endif()
+endfunction()