Tests: Disable UserspaceEmulator tests for Clang builds

There seems to be more incorrect assumptions about Clang-built
executables' memory layout than expected. These make the CI fail even
though the system is functional in all other aspects. While this is
being fixed, let's just disable tests for UserspaceEmulator.

Tests/CMakeLists.txt

@@ -15,7 +15,7 @@ add_subdirectory(LibSQL)
 add_subdirectory(LibUnicode)
 add_subdirectory(LibWasm)
 add_subdirectory(LibWeb)
-if (${SERENITY_ARCH} STREQUAL "i686")
+if (${SERENITY_ARCH} STREQUAL "i686" AND NOT USE_CLANG_TOOLCHAIN)
     add_subdirectory(UserspaceEmulator)
 endif()
 add_subdirectory(LibCrypto)