[USE_CRT_DLL]: Remove unnecessary extern, which

screws up dllimport attributes.

src/callproc.c

@@ -24,7 +24,9 @@ Boston, MA 02111-1307, USA.  */
 #include <errno.h>
 #include <stdio.h>
 
+#ifndef USE_CRT_DLL
 extern int errno;
+#endif
 
 /* Define SIGCHLD as an alias for SIGCLD.  */
 
@@ -88,8 +90,10 @@ extern int errno;
 #ifdef VMS
 extern noshare char **environ;
 #else
+#ifndef USE_CRT_DLL
 extern char **environ;
 #endif
+#endif
 
 #ifdef HAVE_SETPGID
 #if !defined (USG) || defined (BSD_PGRPS)

src/lread.c

@@ -72,7 +72,9 @@ Boston, MA 02111-1307, USA.  */
 #define file_tell ftell
 #endif
 
+#ifndef USE_CRT_DLL
 extern int errno;
+#endif
 
 Lisp_Object Qread_char, Qget_file_char, Qstandard_input, Qcurrent_load_list;
 Lisp_Object Qvariable_documentation, Vvalues, Vstandard_input, Vafter_load_alist;

src/strftime.c

@@ -52,8 +52,10 @@
 # endif
 #endif
 #if HAVE_TZNAME
+#ifndef USE_CRT_DLL
 extern char *tzname[];
 #endif
+#endif
 
 /* Do multibyte processing if multibytes are supported, unless
    multibyte sequences are safe in formats.  Multibyte sequences are