Revert "headers: move the C++ check for interlocked API"

This reverts commit 1013ae930cd6599dbfb181430996791731d18dc1.

This has been fixed properly now, that fix only hid the issue
when compiling in C mode.

Signed-off-by: Martin Storsjö <martin@martin.st>

mingw-w64-headers/include/winbase.h

diff --git a/mingw-w64-headers/include/winbase.h b/mingw-w64-headers/include/winbase.h
index 17025b3..d28b84b 100644
--- a/mingw-w64-headers/include/winbase.h
+++ b/mingw-w64-headers/include/winbase.h
@@ -3051,7 +3051,7 @@
 
 #if !defined (RC_INVOKED) && !defined (NOWINBASEINTERLOCK) && !defined (_NTOS_) && !defined (MICROSOFT_WINDOWS_WINBASE_INTERLOCKED_CPLUSPLUS_H_INCLUDED)
 #define MICROSOFT_WINDOWS_WINBASE_INTERLOCKED_CPLUSPLUS_H_INCLUDED
-#if !defined (__WIDL__) && defined (__cplusplus)
+#if !defined (__WIDL__)
 #if !defined (MICROSOFT_WINDOWS_WINBASE_H_DEFINE_INTERLOCKED_CPLUSPLUS_OVERLOADS)
 #if (_WIN32_WINNT >= 0x0502 || !defined (_WINBASE_))
 #define MICROSOFT_WINDOWS_WINBASE_H_DEFINE_INTERLOCKED_CPLUSPLUS_OVERLOADS 1
@@ -3059,7 +3059,7 @@
 #define MICROSOFT_WINDOWS_WINBASE_H_DEFINE_INTERLOCKED_CPLUSPLUS_OVERLOADS 0
 #endif
 #endif
-#if MICROSOFT_WINDOWS_WINBASE_H_DEFINE_INTERLOCKED_CPLUSPLUS_OVERLOADS
+#if MICROSOFT_WINDOWS_WINBASE_H_DEFINE_INTERLOCKED_CPLUSPLUS_OVERLOADS && defined (__cplusplus)
 extern "C++" {
 #if defined(__x86_64__) && defined(__CYGWIN__)
 #define __MINGW_USE_INT64_INTERLOCKED_LONG