Build mupdf in release mode, not debug.

Thanks to NiLuJe who pointed out that we are building mupdf in debug
mode. Switching to "release" build reduced the size of the kpdfview
binary and did not cause any performance degradation (but no noticeable
improvement either --- the page handling times seem to be exactly the
same, i.e. fluctuating a couple of ms in both directions).

Makefile

@@ -2,7 +2,7 @@
 
 LUADIR=luajit-2.0
 MUPDFDIR=mupdf
-MUPDFTARGET=build/debug
+MUPDFTARGET=build/release
 MUPDFLIBDIR=$(MUPDFDIR)/$(MUPDFTARGET)
 DJVUDIR=djvulibre
 KPVCRLIBDIR=kpvcrlib
@@ -162,7 +162,7 @@ clean:
 
 cleanthirdparty:
 	-make -C $(LUADIR) clean
-	-make -C $(MUPDFDIR) clean
+	-make -C $(MUPDFDIR) build="release" clean
 	-make -C $(CRENGINEDIR)/thirdparty/antiword clean
 	test -d $(CRENGINEDIR)/thirdparty/chmlib && make -C $(CRENGINEDIR)/thirdparty/chmlib clean || echo warn: chmlib folder not found
 	test -d $(CRENGINEDIR)/thirdparty/libpng && (make -C $(CRENGINEDIR)/thirdparty/libpng clean) || echo warn: libpng folder not found
@@ -173,18 +173,18 @@ cleanthirdparty:
 	-rm -f $(MUPDFDIR)/cmapdump.host
 
 $(MUPDFDIR)/fontdump.host:
-	make -C mupdf CC="$(HOSTCC)" $(MUPDFTARGET)/fontdump
+	make -C mupdf build="release" CC="$(HOSTCC)" $(MUPDFTARGET)/fontdump
 	cp -a $(MUPDFLIBDIR)/fontdump $(MUPDFDIR)/fontdump.host
 	make -C mupdf clean
 
 $(MUPDFDIR)/cmapdump.host:
-	make -C mupdf CC="$(HOSTCC)" $(MUPDFTARGET)/cmapdump
+	make -C mupdf build="release" CC="$(HOSTCC)" $(MUPDFTARGET)/cmapdump
 	cp -a $(MUPDFLIBDIR)/cmapdump $(MUPDFDIR)/cmapdump.host
 	make -C mupdf clean
 
 $(MUPDFLIBS) $(THIRDPARTYLIBS): $(MUPDFDIR)/cmapdump.host $(MUPDFDIR)/fontdump.host
 	# build only thirdparty libs, libfitz and pdf utils, which will care for libmupdf.a being built
-	CFLAGS="$(CFLAGS) -DNOBUILTINFONT" make -C mupdf CC="$(CC)" CMAPDUMP=cmapdump.host FONTDUMP=fontdump.host MUPDF= MU_APPS= BUSY_APP= XPS_APPS= verbose=1
+	CFLAGS="$(CFLAGS) -DNOBUILTINFONT" make -C mupdf build="release" CC="$(CC)" CMAPDUMP=cmapdump.host FONTDUMP=fontdump.host MUPDF= MU_APPS= BUSY_APP= XPS_APPS= verbose=1
 
 $(DJVULIBS):
 	-mkdir $(DJVUDIR)/build