make to_vec template parameters explicit
make to_vec template parameters explicit

For some reason, Clang can infer <N,T> but GCC can't.
No big deal... we know exactly the ones we want anyway.

Change-Id: I15ba4d4edbd3bc0f37ebe3c2b6e411726cd9fb69
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/207341
Commit-Queue: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>
Reviewed-by: Michael Ludwig <cb1f3dd24de0f0b611b26bc28bec758a551d9b7d@google.com>

rubenvb/skia,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,rubenvb/skia,rubenvb/skia,google/skia,google/skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,google/skia,rubenvb/skia,rubenvb/skia,rubenvb/skia,rubenvb/skia,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia