Try fixing ABI feature detection

Author: ldionne

libcxx/utils/libcxx/test/dsl.py

@@ -308,8 +308,8 @@ def compilerMacros(config, flags=""):
         with open(test.getSourcePath(), "w") as sourceFile:
             sourceFile.write(
                 """
-      #if __has_include(<__config_site>)
-      #  include <__config_site>
+      #if __has_include(<__config>)
+      #  include <__config>
       #endif
       """
             )

libcxx/utils/libcxx/test/features.py

@@ -335,10 +335,10 @@ def _mingwSupportsModules(cfg):
 ]
 
 # Deduce and add the test features that that are implied by the #defines in
-# the <__config_site> header.
+# the <__config> header.
 #
 # For each macro of the form `_LIBCPP_XXX_YYY_ZZZ` defined below that
-# is defined after including <__config_site>, add a Lit feature called
+# is defined after including <__config>, add a Lit feature called
 # `libcpp-xxx-yyy-zzz`. When a macro is defined to a specific value
 # (e.g. `_LIBCPP_ABI_VERSION=2`), the feature is `libcpp-xxx-yyy-zzz=<value>`.
 #