OSV-2020-1712 Use-of-uninitialized-value in gx_color_frac_map

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=25463 Crash type: Use-of-uninitialized-value Crash state: gxcolorfracmap pdf14cmaprgbdirect gxremapconcreteDRGB...