Avoid translating simple error exceptions

These are very rare and very low level. Might as well just print
the offending call to keep things easily maintained.
diff --git a/vncviewer/OSXPixelBuffer.cxx b/vncviewer/OSXPixelBuffer.cxx
index e9100f2..d04d9b3 100644
--- a/vncviewer/OSXPixelBuffer.cxx
+++ b/vncviewer/OSXPixelBuffer.cxx
@@ -49,13 +49,13 @@
 
   lut = CGColorSpaceCreateDeviceRGB();
   if (!lut)
-    throw rfb::Exception(_("Could not create framebuffer device"));
+    throw rfb::Exception("CGColorSpaceCreateDeviceRGB");
 
   bitmap = CGBitmapContextCreate(data, width, height, 8, width*4, lut,
                                  kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Little);
   CGColorSpaceRelease(lut);
   if (!bitmap)
-    throw rfb::Exception(_("Could not create framebuffer bitmap"));
+    throw rfb::Exception("CGBitmapContextCreate");
 }
 
 
diff --git a/vncviewer/Win32PixelBuffer.cxx b/vncviewer/Win32PixelBuffer.cxx
index 3f82530..002d4c8 100644
--- a/vncviewer/Win32PixelBuffer.cxx
+++ b/vncviewer/Win32PixelBuffer.cxx
@@ -57,10 +57,8 @@
 
   bitmap = CreateDIBSection(NULL, (BITMAPINFO*)&bih,
                             DIB_RGB_COLORS, (void**)&data, NULL, 0);
-  if (!bitmap) {
-    int err = GetLastError();
-    throw rdr::SystemException(_("unable to create DIB section"), err);
-  }
+  if (!bitmap)
+    throw rdr::SystemException("CreateDIBSection", GetLastError());
 }
 
 
@@ -76,10 +74,10 @@
 
   dc = CreateCompatibleDC(fl_gc);
   if (!dc)
-    throw rdr::SystemException(_("CreateCompatibleDC failed"), GetLastError());
+    throw rdr::SystemException("CreateCompatibleDC", GetLastError());
 
   if (!SelectObject(dc, bitmap))
-    throw rdr::SystemException(_("SelectObject failed"), GetLastError());
+    throw rdr::SystemException("SelectObject", GetLastError());
 
   if (!BitBlt(fl_gc, x, y, w, h, dc, src_x, src_y, SRCCOPY)) {
     // If the desktop we're rendering to is inactive (like when the screen
@@ -88,7 +86,7 @@
     // with it. For now, we've only seen this error and for this function
     // so only ignore this combination.
     if (GetLastError() != ERROR_INVALID_HANDLE)
-      throw rdr::SystemException(_("BitBlt failed"), GetLastError());
+      throw rdr::SystemException("BitBlt", GetLastError());
   }
 
   DeleteDC(dc);
diff --git a/vncviewer/X11PixelBuffer.cxx b/vncviewer/X11PixelBuffer.cxx
index ce5c4d8..a1d7687 100644
--- a/vncviewer/X11PixelBuffer.cxx
+++ b/vncviewer/X11PixelBuffer.cxx
@@ -110,11 +110,13 @@
     xim = XCreateImage(fl_display, fl_visual->visual, fl_visual->depth,
                        ZPixmap, 0, 0, width, height, BitmapPad(fl_display), 0);
     if (!xim)
-      throw rfb::Exception(_("Could not create framebuffer image"));
+      throw rfb::Exception("XCreateImage");
 
     xim->data = (char*)malloc(xim->bytes_per_line * xim->height);
     if (!xim->data)
       throw rfb::Exception(_("Not enough memory for framebuffer"));
+
+    vlog.debug("Using standard XImage");
   }
 
   data = (rdr::U8*)xim->data;