Patch stolen from Mageia Cauldron but had to be modified quite a bit.

diff --git a/filters/karbon/pdf/SvgOutputDev.cpp b/filters/karbon/pdf/SvgOutputDev.cpp
index ffdbf01..70bc9f8 100644
--- a/filters/karbon/pdf/SvgOutputDev.cpp
+++ b/filters/karbon/pdf/SvgOutputDev.cpp
@@ -405,7 +405,7 @@ void SvgOutputDev::drawString(GfxState * state, GooString * s)
     const char * p = s->c_str();
     int len = s->getLength();
     CharCode code;
-    Unicode *u = nullptr;
+    const Unicode *u = nullptr;
     int uLen;
     double dx, dy, originX, originY;
     while (len > 0) {
@@ -545,7 +545,7 @@ void SvgOutputDev::drawImage(GfxState *state, Object */*ref*/, Stream *str,
 
 void SvgOutputDev::drawImage(GfxState *state, Object *ref, Stream *str,
                              int width, int height, GfxImageColorMap *colorMap,
-                             bool /*interpolate*/, int *maskColors, bool inlineImg)
+                             bool /*interpolate*/, const int *maskColors, bool inlineImg)
 {
     drawImage(state, ref, str, width, height, colorMap, maskColors, inlineImg);
 }
--- a/filters/karbon/pdf/SvgOutputDev.h
+++ b/filters/karbon/pdf/SvgOutputDev.h
@@ -63,7 +63,7 @@ public:
     // images
     void drawImage(GfxState *state, Object *ref, Stream *str,
                            int width, int height, GfxImageColorMap *colorMap,
-                           bool interpolate, int *maskColors, bool inlineImg) override;
+                           bool interpolate, const int *maskColors, bool inlineImg) override;
 
     // styles
     virtual void updateAll(GfxState *state);