OSV-2018-384 Use-of-uninitialized-value in template_affine_N_lerp

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5616 Crash type: Use-of-uninitialized-value Crash state: templateaffineNlerp paintaffinelerpdasa0 fzpaintimageimp...