Made has-config-flag more flexible.

The has-config-flag rule now matches any value of the checked macro and
is able to test multiple macros in one call.

Author: Lastique

build/Jamfile.v2

@@ -1,7 +1,7 @@
 # Boost Filesystem Library Build Jamfile
 
 # (C) Copyright Beman Dawes 2002-2006
-# (C) Copyright Andrey Semashev 2020-2024
+# (C) Copyright Andrey Semashev 2020-2025
 # Distributed under the Boost Software License, Version 1.0.
 # See www.boost.org/LICENSE_1_0.txt
 
@@ -17,17 +17,21 @@ lib advapi32 ;
 lib coredll ;
 explicit bcrypt advapi32 coredll ;
 
-# The rule checks if a config macro is defined in the command line or build properties
-rule has-config-flag ( flag : properties * )
+# The rule checks if there is one of the defines listed in `flags` in `properties`. The value of the define is not considered.
+rule has-config-flag ( flags + : properties * )
 {
-    if ( "<define>$(flag)" in $(properties) || "<define>$(flag)=1" in $(properties) )
+    for local property in $(properties)
     {
-        return 1 ;
-    }
-    else
-    {
-        return ;
+        for local flag in $(flags)
+        {
+            if [ MATCH "^(<define>$(flag))(=.*)?$" : $(property) ]
+            {
+                return 1 ;
+            }
+        }
     }
+
+    return ;
 }
 
 # The rule checks we're building for Windows and selects crypto API to be used