crengine: drop unnecessary MuPDF dependency (koreader#1700)

We're using the `jconfig.h` header provided by `libjpeg-turbo` anyway.

Makefile.third

@@ -259,7 +259,6 @@ $(CRENGINE_LIB) $(CRENGINE_THIRDPARTY_LIBS): $(CRENGINE_SRC_FILES) \
 		$(LIBUNIBREAK_DIR)/include \
 		$(LIBWEBP_DIR)/include \
 		$(LUNASVG_DIR)/include \
-		$(MUPDF_DIR)/scripts \
 		$(PNG_DIR)/include \
 		$(SRELL_INCLUDE_DIR) \
 		$(UTF8PROC_DIR) \
@@ -270,7 +269,6 @@ $(CRENGINE_LIB) $(CRENGINE_THIRDPARTY_LIBS): $(CRENGINE_SRC_FILES) \
 	cd $(CRENGINE_BUILD_DIR) && \
 		$(CMAKE) $(CMAKE_FLAGS) \
 		-DJPEGLIB_INCLUDE_DIR='$(JPEG_DIR)/include' \
-		-DJCONFIG_INCLUDE_DIR='$(MUPDF_DIR)/scripts' \
 		-DPNG_INCLUDE_DIR='$(PNG_DIR)/include' \
 		-DLUNASVG_INCLUDE_DIR='$(LUNASVG_DIR)/include' \
 		-DZLIB_INCLUDE_DIR='$(ZLIB_DIR)/include' \

thirdparty/kpvcrlib/CMakeLists.txt

@@ -19,7 +19,6 @@ set(ANTIWORD_INCLUDE_DIR ${CR_3RDPARTY_DIR}/antiword)
 set(CHM_INCLUDE_DIRS ${CR_3RDPARTY_DIR}/chmlib/src)
 set(CREGINE_INCLUDE_DIR ${CRE_DIR}/include)
 
-assert_var_defined(JCONFIG_INCLUDE_DIR)
 assert_var_defined(FREETYPE_INCLUDE_DIR)
 assert_var_defined(HARFBUZZ_INCLUDE_DIR)
 assert_var_defined(FRIBIDI_INCLUDE_DIR)
@@ -33,7 +32,6 @@ assert_var_defined(LUNASVG_INCLUDE_DIR)
 assert_var_defined(ZSTD_INCLUDE_DIR)
 
 include_directories(
-    ${JCONFIG_INCLUDE_DIR}
     ${FREETYPE_INCLUDE_DIR}
     ${HARFBUZZ_INCLUDE_DIR}
     ${FRIBIDI_INCLUDE_DIR}