[AC21.5 ?21.4] Fix C++ build on Gentoo

[Stephen J. Turnbull]

APPROVE COMMIT 21.5

I don't know if this is appropriate for 21.4.

Thanks to Vladimir G. Ivanovic for the report.

I'm not sure why this should matter, I thought variables should have
the same linkage in C and C++.  However Gentoo's GCC 4.1 or so does
complain.

Index: src/ChangeLog
===================================================================
RCS file: /pack/xemacscvs/XEmacs/xemacs/src/ChangeLog,v
retrieving revision 1.1071
diff -u -r1.1071 ChangeLog
--- src/ChangeLog	22 Jun 2007 17:15:34 -0000	1.1071
+++ src/ChangeLog	22 Jun 2007 17:19:39 -0000
@@ -0,0 +1,4 @@
+2007-06-23  Stephen J. Turnbull  <stephen at xemacs.org>
+
+	* sysdep.h (environ): Needs to be in C_DECLS for C++ build.
+

Index: src/sysdep.h
===================================================================
RCS file: /pack/xemacscvs/XEmacs/xemacs/src/sysdep.h,v
retrieving revision 1.22
diff -u -r1.22 sysdep.h
--- src/sysdep.h	25 Feb 2004 20:05:33 -0000	1.22
+++ src/sysdep.h	22 Jun 2007 17:19:39 -0000
@@ -26,10 +26,6 @@
 
 #include <setjmp.h>
 
-#ifndef WIN32_NATIVE
-extern char **environ;
-#endif
-
 #ifdef PDUMP
 int pdump_read_file (char **pdump_start_pos, size_t *pdump_length);
 #endif
@@ -67,6 +63,10 @@
 void unrequest_sigio (void);
 
 BEGIN_C_DECLS
+
+#ifndef WIN32_NATIVE
+extern char **environ;
+#endif
 
 void stop_interrupts (void);
 void start_interrupts (void);