Conditionally fix name of zlib that the linker needs (#104904)

* Conditionally fix the name of zlib that the linker needs

* Remove the android branch, add a comment to explain when z and zlib are used.

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Co-authored-by: Carlos Sánchez López <1175054+carlossanlop@users.noreply.github.com>
Co-authored-by: Adeel Mujahid <3840695+am11@users.noreply.github.com>

src/native/libs/System.IO.Compression.Native/extra_libs.cmake

@@ -3,17 +3,20 @@ macro(append_extra_compression_libs NativeLibsExtra)
   # TODO: remove the mono-style HOST_ variable checks once Mono is using eng/native/configureplatform.cmake to define the CLR_CMAKE_TARGET_ defines
   if (CLR_CMAKE_TARGET_BROWSER OR HOST_BROWSER OR CLR_CMAKE_TARGET_WASI OR HOST_WASI)
       # nothing special to link
-  elseif (CLR_CMAKE_TARGET_ANDROID OR HOST_ANDROID)
-      # need special case here since we want to link against libz.so but find_package() would resolve libz.a
-      list(APPEND ZLIB_LIBRARIES z)
   elseif (CLR_CMAKE_HOST_ARCH_ARMV6)
       find_package(ZLIB REQUIRED)
       list(APPEND ZLIB_LIBRARIES z)
   elseif (CLR_CMAKE_TARGET_MACCATALYST OR CLR_CMAKE_TARGET_IOS OR CLR_CMAKE_TARGET_TVOS)
       find_package(ZLIB REQUIRED)
       list(APPEND ZLIB_LIBRARIES m)
   else()
-    list(APPEND ZLIB_LIBRARIES zlib)
+    # 'z' is used in:
+    # - Platforms that set CMAKE_USE_SYSTEM_ZLIB to true, like Android.
+    # - When it is set to true via CLI using --cmakeargs.
+    # 'zlib' represents our in-tree zlib, and is used in all other platforms
+    # that don't meet any of the previous special requirements, like most
+    # regular Unix and Windows builds.
+    list(APPEND ZLIB_LIBRARIES $<IF:$<BOOL:CLR_CMAKE_USE_SYSTEM_ZLIB>,z,zlib>)
   endif ()
   list(APPEND ${NativeLibsExtra} ${ZLIB_LIBRARIES})