use C++ compiler for va_copy test, at least under IRIX the C99 C compiler has it but C++ compiler doesn't have it [backport from HEAD]

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@46031 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

configure

@@ -21270,6 +21270,12 @@ if test "${wx_cv_func_va_copy+set}" = set; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
 else
 
+        ac_ext=cc
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
         cat >conftest.$ac_ext <<_ACEOF
 
             #include <stdarg.h>
@@ -21296,7 +21302,7 @@ if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
   cat conftest.err >&5
   echo "$as_me:$LINENO: \$? = $ac_status" >&5
   (exit $ac_status); } &&
-	 { ac_try='test -z "$ac_c_werror_flag"			 || test ! -s conftest.err'
+	 { ac_try='test -z "$ac_cxx_werror_flag"			 || test ! -s conftest.err'
   { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
   (eval $ac_try) 2>&5
   ac_status=$?
@@ -21318,6 +21324,12 @@ wx_cv_func_va_copy=no
 fi
 rm -f conftest.err conftest.$ac_objext \
       conftest$ac_exeext conftest.$ac_ext
+        ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
 
 
 fi

configure.in

@@ -1922,6 +1922,7 @@ dnl checks needed to define wxVaCopy
 AC_CACHE_CHECK([for va_copy],
     wx_cv_func_va_copy,
     [
+        AC_LANG_PUSH(C++)
         AC_LINK_IFELSE([
             #include <stdarg.h>
             void foo(char *f, ...)
@@ -1940,6 +1941,7 @@ AC_CACHE_CHECK([for va_copy],
             wx_cv_func_va_copy=yes,
             wx_cv_func_va_copy=no
         )
+        AC_LANG_POP()
     ]
 )