Unix interop uses non-posix open64

[kangaroo]

The unix interop layer currently pinvokes open64. open64 is a non-POSIX extension. We should move to using open() with O_LARGEFILE.

This currently blocks using System.Console and System.IO on osx.

[kangaroo]

Trivial fix without O_LARGEFILE:

diff --git a/src/Common/src/Interop/Unix/libc/Interop.open64.cs b/src/Common/src/Interop/Unix/libc/Interop.open64.cs
index d5810ce..e6ec079 100644
--- a/src/Common/src/Interop/Unix/libc/Interop.open64.cs
+++ b/src/Common/src/Interop/Unix/libc/Interop.open64.cs
@@ -11,7 +11,7 @@ internal static partial class Interop
     internal static partial class libc
     {
         [DllImport(Libraries.Libc, SetLastError = true)]
-        internal static extern int open64(string filename, OpenFlags flags, mode_t mode);
+        internal static extern int open(string filename, OpenFlags flags, mode_t mode);

         [Flags]
         internal enum OpenFlags
diff --git a/src/Common/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs b/src/Common/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs
index e7cf81c..49f0bed 100644
--- a/src/Common/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs
+++ b/src/Common/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs
@@ -38,7 +38,7 @@ namespace Microsoft.Win32.SafeHandles
             try { } finally
             {
                 int fd;
-                while (Interop.CheckIo(fd = Interop.libc.open64(path, flags, mode))) ;
+                while (Interop.CheckIo(fd = Interop.libc.open(path, flags, mode))) ;
                 Contract.Assert(fd >= 0);
                 handle.SetHandle((IntPtr)fd);
             }
diff --git a/src/System.Console/src/System/ConsolePal.Unix.cs b/src/System.Console/src/System/ConsolePal.Unix.cs
index a51ab83..b3de57c 100644
--- a/src/System.Console/src/System/ConsolePal.Unix.cs
+++ b/src/System.Console/src/System/ConsolePal.Unix.cs
@@ -448,7 +448,7 @@ namespace System
                     string filePath = directoryPath + "/" + term[0] + "/" + term; // filePath == /directory/termFirstLetter/term

                     int fd;
-                    while ((fd = Interop.libc.open64(filePath, Interop.libc.OpenFlags.O_RDONLY, 0)) < 0)
+                    while ((fd = Interop.libc.open(filePath, Interop.libc.OpenFlags.O_RDONLY, 0)) < 0)
                     {
                         // Don't throw in this case, as we'll be polling multiple locations looking for the file.
                         // But we still want to retry if the open is interrupted by a signal.

[stephentoub]

Thanks, @kangaroo. I'll fix this.