Fix runtime errors found by clang's sanitizer (#47082).

* src/base/ftobjs.c (FT_Render_Glyph_Internal), src/base/ftoutln.c
(FT_Outline_Copy), src/cache/ftcsbits.c (ftc_sbit_copy_bitmap):
Properly handle empty input buffer.

ChangeLog

@@ -1,3 +1,11 @@
+2016-02-07  Werner Lemberg  <wl@gnu.org>
+
+	Fix runtime errors found by clang's sanitizer (#47082).
+
+	* src/base/ftobjs.c (FT_Render_Glyph_Internal), src/base/ftoutln.c
+	(FT_Outline_Copy), src/cache/ftcsbits.c (ftc_sbit_copy_bitmap):
+	Properly handle empty input buffer.
+
 2016-02-07  Werner Lemberg  <wl@gnu.org>
 
 	[cff] Minor.

src/base/ftobjs.c

@@ -4201,6 +4201,7 @@
 
 
           MD5_Init( &ctx );
+          if ( bitmap.buffer )
             MD5_Update( &ctx, bitmap.buffer, rows * pitch );
           MD5_Final( md5, &ctx );
 

src/base/ftoutln.c

@@ -415,10 +415,13 @@
     if ( source == target )
       return FT_Err_Ok;
 
+    if ( source->n_points )
+    {
       FT_ARRAY_COPY( target->points, source->points, source->n_points );
-
       FT_ARRAY_COPY( target->tags,   source->tags,   source->n_points );
+    }
 
+    if ( source->n_contours )
       FT_ARRAY_COPY( target->contours, source->contours, source->n_contours );
 
     /* copy all flags, except the `FT_OUTLINE_OWNER' one */

src/cache/ftcsbits.c

@@ -53,6 +53,8 @@
       pitch = -pitch;
 
     size = (FT_ULong)pitch * bitmap->rows;
+    if ( !size )
+      return FT_Err_Ok;
 
     if ( !FT_ALLOC( sbit->buffer, size ) )
       FT_MEM_COPY( sbit->buffer, bitmap->buffer, size );