Don't automatically case-correct mispelled package-names
Previously, a command like cabal install uHttpc would silently auto-correct this to cabal install uhttpc However, this is inconsistent as `build-depends` or `constraints` are case-insensitive. So with this patch, cabal install VULKAN uHttpc result in the following error(s) instead: There is no package named 'VULKAN'. However, the following package names exist: 'Vulkan', 'vulkan'. There is no package named 'uHttpc'. However, the following package name exists: 'uhttpc'.