test for round() using C++ compiler, not C one (should fix IRIX mipsPro build)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@45917 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

configure

@@ -35473,6 +35473,12 @@ _ACEOF
 
 fi
 
+ac_ext=cpp
+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
+
 
   for wx_func in round
   do
@@ -35521,7 +35527,7 @@ eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
   cat conftest.err >&5
   echo "$as_me:$LINENO: \$? = $ac_status" >&5
   (exit $ac_status); } && {
-	 test -z "$ac_c_werror_flag" ||
+	 test -z "$ac_cxx_werror_flag" ||
 	 test ! -s conftest.err
        } && test -s conftest$ac_exeext &&
        $as_test_x conftest$ac_exeext; then
@@ -35554,6 +35560,12 @@ _ACEOF
     fi
   done
 
+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
+
 
 if test "$TOOLKIT" != "MSW"; then
 

configure.in

@@ -4703,7 +4703,11 @@ if test "$wxUSE_FILE" = "yes"; then
     WX_CHECK_FUNCS(fsync)
 fi
 
+dnl at least under IRIX with mipsPro the C99 round() function is available when
+dnl building using the C compiler but not when using C++ one
+AC_LANG_PUSH(C++)
 WX_CHECK_FUNCS(round,,,[#include <math.h>])
+AC_LANG_POP()
 
 dnl the following tests are for Unix(like) systems only
 if test "$TOOLKIT" != "MSW"; then