use small_vector in more places #749

Job	Run time
msvc-x64, Release, Shared=ON	5m 28s
msvc-x64, Release, Shared=OFF	5m 37s
clang-x64, Release, Shared=ON	8m 10s
clang-x64, Release, Shared=OFF	9m 45s
msvc-x64, RelWithDebInfo, Shared=ON	6m 16s
msvc-x64, RelWithDebInfo, Shared=OFF	5m 53s
clang-x64, RelWithDebInfo, Shared=ON	9m 15s
clang-x64, RelWithDebInfo, Shared=OFF	10m 45s
msvc-Win32, RelWithDebInfo, Shared=ON	6m 58s
msvc-Win32, RelWithDebInfo, Shared=OFF	5m 6s
clang-Win32, RelWithDebInfo, Shared=ON	9m 5s
clang-Win32, RelWithDebInfo, Shared=OFF	8m 5s
	1h 30m 23s

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