Please use cmake standard usage, which makes it optionally possible to use ninja instead of make, if it is configured by environment variable CMAKE_GENERATOR=Ninja:
cmake --build .
and
cmake --install . --prefix="$pkgdir/usr"
Then the two following lines can be removed, too:
mv "${pkgdir}/usr/local/"* "${pkgdir}/usr/"
rm -r "${pkgdir}/usr/local"
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