Define GC_DLL if DLL_EXPORT at GC build

(Apply part of commit 6488760 from 'gcc_boehmgc' branch.)

* include/gc_config_macros.h (GC_DLL): Define if we are actually in GC
build and DLL_EXPORT is defined (unless prohibited by GC_NOT_DLL)
preventing GC internal symbols exporting on Cygwin and MinGW.

diff --git a/include/gc_config_macros.h b/include/gc_config_macros.h
index b340f4998a463864447317d8f74587eb0e7b5baa..d4b72313b45ac3a831eaa01a3338fe21fbb57c91 100644 (file)
--- a/include/gc_config_macros.h
+++ b/include/gc_config_macros.h
@@ -164,8 +164,9 @@
 # endif
 #endif /* _WIN32_WCE */
 
-#if defined(_DLL) && !defined(GC_NOT_DLL) && !defined(GC_DLL) \
-        && !defined(__GNUC__)
+#if !defined(GC_NOT_DLL) && !defined(GC_DLL) \
+    && ((defined(_DLL) && !defined(__GNUC__)) \
+        || (defined(DLL_EXPORT) && defined(GC_BUILD)))
 # define GC_DLL
 #endif