vpImage::getStdev specialization #1661

Job	Run time
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 11)	26m 50s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 14)	27m 12s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-9, /usr/bin/g++-9, 17)	29m 54s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 11)	24m 1s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 14)	24m 32s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/gcc-10, /usr/bin/g++-10, 17)	27m 48s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 11)	31m 29s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 14)	32m 17s
build-ubuntu-dep-apt (ubuntu-20.04, /usr/bin/clang, /usr/bin/clang++, 17)	33m 48s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 11)	22m 25s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 14)	23m 15s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-9, /usr/bin/g++-9, 17)	25m 45s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 11)	24m 34s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 14)	24m 51s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/gcc-10, /usr/bin/g++-10, 17)	28m 16s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 11)	33m 26s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 14)	33m 16s
build-ubuntu-dep-apt (ubuntu-22.04, /usr/bin/clang, /usr/bin/clang++, 17)	36m 2s
	8h 29m 41s

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