Unbreak check-all on macOS after dbe8c2c316c40

`${X86_64}` expands to `x86_64;x86_64h` on macOS, so

    get_test_cc_for_arch(${X86_64} METADATA_TEST_TARGET_CC METADATA_TEST_TARGET_CFLAGS)

calls the macro get_test_cc_for_arch() with the four arguments
`x86_64`, `x86_64h`, `METADATA_TEST_TARGET_CC`, and `METADATA_TEST_TARGET_CFLAGS`.

This writes the compiler into a variable called x86_64h, the cflags into a
variable called METADATA_TEST_TARGET_CC, and silently ignores the fourth
parameter.

As a fix, just pass `x86_64` instead of `${X86_64}`. Hopefully
that won't break anything on other platforms.

GitOrigin-RevId: 9531fc37fb8b84e448144fc2318e28fa0654a47e
diff --git a/test/metadata/CMakeLists.txt b/test/metadata/CMakeLists.txt
index 7f1befb..3391a89 100644
--- a/test/metadata/CMakeLists.txt
+++ b/test/metadata/CMakeLists.txt
@@ -5,7 +5,7 @@
   set(METADATA_LIT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 
   set(SANITIZER_COMMON_TEST_TARGET_ARCH ${X86_64})
-  get_test_cc_for_arch(${X86_64} METADATA_TEST_TARGET_CC METADATA_TEST_TARGET_CFLAGS)
+  get_test_cc_for_arch(x86_64 METADATA_TEST_TARGET_CC METADATA_TEST_TARGET_CFLAGS)
   configure_lit_site_cfg(
     ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
     ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py)