gdiplus: Fix some memory leaks

[Andrew Talbot]

Changelog:
    gdiplus: Fix some memory leaks.

diff --git a/dlls/gdiplus/graphics.c b/dlls/gdiplus/graphics.c
index 3072b50..c69c0e5 100644
--- a/dlls/gdiplus/graphics.c
+++ b/dlls/gdiplus/graphics.c
@@ -1418,6 +1418,7 @@ GpStatus WINGDIPAPI GdipDrawString(GpGra
             break;
     }
 
+    GdipFree(stringdup);
     DeleteObject(rgn);
     DeleteObject(gdifont);
 
@@ -1827,6 +1828,7 @@ GpStatus WINGDIPAPI GdipMeasureString(Gp
     bounds->Width = (REAL)max_width;
     bounds->Height = (REAL) min(height, nheight);
 
+    GdipFree(stringdup);
     DeleteObject(SelectObject(graphics->hdc, oldfont));
 
     return Ok;