Fix grammar in cairo_*_reference() function documentation.

"can be get" is incorrect grammar; "can be gotten" would be better, but
active voice is best.

Signed-off-by: Bryce Harrington <bryce@bryceharrington.org>

src/cairo-device.c

@@ -194,8 +194,8 @@ _cairo_device_init (cairo_device_t *device,
  * @device from being destroyed until a matching call to
  * cairo_device_destroy() is made.
  *
- * The number of references to a #cairo_device_t can be get using
- * cairo_device_get_reference_count().
+ * Use cairo_device_get_reference_count() to get the number of references
+ * to a #cairo_device_t.
  *
  * Return value: the referenced #cairo_device_t.
  *

src/cairo-font-face.c

@@ -111,8 +111,8 @@ _cairo_font_face_init (cairo_font_face_t               *font_face,
  * @font_face from being destroyed until a matching call to
  * cairo_font_face_destroy() is made.
  *
- * The number of references to a #cairo_font_face_t can be get using
- * cairo_font_face_get_reference_count().
+ * Use cairo_font_face_get_reference_count() to get the number of
+ * references to a #cairo_font_face_t.
  *
  * Return value: the referenced #cairo_font_face_t.
  *

src/cairo-pattern.c

@@ -1047,8 +1047,8 @@ cairo_pattern_create_mesh (void)
  * @pattern from being destroyed until a matching call to
  * cairo_pattern_destroy() is made.
  *
- * The number of references to a #cairo_pattern_t can be get using
- * cairo_pattern_get_reference_count().
+ * Use cairo_pattern_get_reference_count() to get the number of
+ * references to a #cairo_pattern_t.
  *
  * Return value: the referenced #cairo_pattern_t.
  *

src/cairo-scaled-font.c

@@ -1277,8 +1277,8 @@ _cairo_scaled_font_reset_static_data (void)
  * @scaled_font from being destroyed until a matching call to
  * cairo_scaled_font_destroy() is made.
  *
- * The number of references to a #cairo_scaled_font_t can be get using
- * cairo_scaled_font_get_reference_count().
+ * Use cairo_scaled_font_get_reference_count() to get the number of
+ * references to a #cairo_scaled_font_t.
  *
  * Returns: the referenced #cairo_scaled_font_t
  *

src/cairo-surface.c

@@ -914,8 +914,8 @@ _cairo_surface_create_scratch (cairo_surface_t	 *other,
  * @surface from being destroyed until a matching call to
  * cairo_surface_destroy() is made.
  *
- * The number of references to a #cairo_surface_t can be get using
- * cairo_surface_get_reference_count().
+ * Use cairo_surface_get_reference_count() to get the number of
+ * references to a #cairo_surface_t.
  *
  * Return value: the referenced #cairo_surface_t.
  *

src/cairo.c

@@ -478,8 +478,8 @@ _cairo_init (cairo_t *cr,
  * @cr from being destroyed until a matching call to cairo_destroy()
  * is made.
  *
- * The number of references to a #cairo_t can be get using
- * cairo_get_reference_count().
+ * Use cairo_get_reference_count() to get the number of references to
+ * a #cairo_t.
  *
  * Return value: the referenced #cairo_t.
  *