Pass linker flags to Mono build on Android correctly (#51403)

We were setting `_MonoLDFLAGS` in mono.proj but never passed the values down into CMake.

src/libraries/Native/Unix/configure.cmake

@@ -60,7 +60,7 @@ endif()
 # Older CMake versions (3.8) do not assign the result of their tests, causing unused-value errors
 # which are not distinguished from the test failing. So no error for that one.
 # For clang-5.0 avoid errors like "unused variable 'err' [-Werror,-Wunused-variable]".
-set(CMAKE_REQUIRED_FLAGS "-Werror -Wno-error=unused-value -Wno-error=unused-variable")
+set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror -Wno-error=unused-value -Wno-error=unused-variable")
 
 # Apple platforms like macOS/iOS allow targeting older operating system versions with a single SDK,
 # the mere presence of a symbol in the SDK doesn't tell us whether the deployment target really supports it.

src/mono/CMakeLists.txt

@@ -213,6 +213,9 @@ elseif(CMAKE_SYSTEM_NAME STREQUAL "Android")
   set(HOST_LINUX 1)
   add_definitions(-D_GNU_SOURCE -D_REENTRANT)
   add_definitions(-D_THREAD_SAFE)
+  add_compile_options(-Wl,-z,now)
+  add_compile_options(-Wl,-z,relro)
+  add_compile_options(-Wl,-z,noexecstack)
   # The normal check fails because it uses --isystem <ndk root>/sysroot/usr/include
   set(HAVE_USR_INCLUDE_MALLOC_H 1)
   set(HOST_ANDROID 1)

src/mono/mono.proj

@@ -249,7 +249,6 @@
       <_MonoCMakeArgs Include="-DCMAKE_OSX_DEPLOYMENT_TARGET=$(macOSVersionMin)" />
       <_MonoCFLAGS Condition="'$(TargetArchitecture)' == 'arm64'" Include="-arch arm64" />
       <_MonoCXXFLAGS Condition="'$(TargetArchitecture)' == 'arm64'" Include="-arch arm64" />
-      <_MonoLDFLAGS Condition="'$(TargetArchitecture)' == 'arm64'" Include="-arch arm64" />
       <!-- Force running as arm64 even when invoked from an x86 msbuild process -->
       <_MonoBuildEnv Condition="'$(BuildArchitecture)' == 'arm64'" Include="arch -arch arm64" />
     </ItemGroup>
@@ -264,7 +263,6 @@
       <_MonoCXXFlags Condition="'$(TargetArchitecture)' == 'arm64'" Include="-target arm64-apple-ios14.2-macabi" />
       <_MonoCXXFlags Condition="'$(TargetArchitecture)' == 'x64'" Include="-target x86_64-apple-ios13.5-macabi" />
       <_MonoCXXFLAGS Condition="'$(TargetArchitecture)' == 'arm64'" Include="-arch arm64" />
-      <_MonoLDFLAGS Condition="'$(TargetArchitecture)' == 'arm64'" Include="-arch arm64" />
       <!-- Force running as arm64 even when invoked from an x86 msbuild process -->
       <_MonoBuildEnv Condition="'$(BuildArchitecture)' == 'arm64'" Include="arch -arch arm64" />
     </ItemGroup>
@@ -378,15 +376,6 @@
       <_MonoCXXFLAGS Condition="'$(Platform)' == 'arm64' or '$(Platform)' == 'arm'" Include="-DSK_RELEASE" />
       <_MonoCXXFLAGS Condition="'$(Platform)' == 'arm64' or '$(Platform)' == 'arm'" Include="-DNDEBUG" />
       <_MonoCXXFLAGS Condition="'$(Platform)' == 'arm64' or '$(Platform)' == 'arm'" Include="-UDEBUG" />
-
-      <_MonoLDFLAGS Include="-z now" />
-      <_MonoLDFLAGS Include="-z relro" />
-      <_MonoLDFLAGS Include="-z noexecstack" />
-      <_MonoLDFLAGS Include="-ldl" />
-      <_MonoLDFLAGS Include="-lm" />
-      <_MonoLDFLAGS Include="-llog" />
-      <_MonoLDFLAGS Include="-lc" />
-      <_MonoLDFLAGS Include="-lgcc" />
     </ItemGroup>
     <!-- Linux options -->
     <ItemGroup Condition="'$(TargetsLinux)' == true">