Use ld_classic when building with XCode 15

XCode 15 toolchain breaks the compatibility for
macOS version older than 12

CMakeLists.txt

@@ -154,18 +154,25 @@ set( _OPT "audacity_" )
 # Our very own project
 project( Audacity )
 
-# XCode 14 no longer allows building unsigned binaries.
-# So for the XCode 14 `-` is passed as the code sign identity, which stands for
-# local signing. `--deep` is passed, because 3d party libraries are copied unsigned.
-# XCODE_VERSION is defined only after the project() command
-
 if( APPLE )
+   # XCode 14 no longer allows building unsigned binaries.
+   # So for the XCode 14 `-` is passed as the code sign identity, which stands for
+   # local signing. `--deep` is passed, because 3d party libraries are copied unsigned.
+   # XCODE_VERSION is defined only after the project() command
    if (XCODE_VERSION VERSION_LESS 14)
       set( CMAKE_XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY "" CACHE INTERNAL "" )
    else()
       set( CMAKE_XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY "-" CACHE INTERNAL "" )
       set( CMAKE_XCODE_ATTRIBUTE_OTHER_CODE_SIGN_FLAGS "--deep -o linker-signed --timestamp" CACHE INTERNAL "")
    endif()
+
+   # Xcode 15 breaks compatibility with macOS vesions older than 12
+   # https://developer.apple.com/documentation/xcode-release-notes/xcode-15-release-notes#Linking
+   if (XCODE_VERSION VERSION_GREATER_EQUAL 15)
+      # link_libraries is guaranteed to set the flag for all
+      # linker invocations
+      link_libraries("-Wl,-ld_classic")
+   endif()
 endif()
 
 # Load our functions/macros