Force line ending of '.in' files in jemalloc to LF

This fixes issue #8731 . On Windows, if the git option core.autocrlf is true (github recommends users to turn on this flag - see https://help.github.com/articles/dealing-with-line-endings), the headers generated from the .in files will have syntatic errors, causing compilation to fail.
auto merge of #8738 : mukilan/rust/master, r=thestinger

This fixes issue #8731 . On Windows, if the git option core.autocrlf is true (github recommends users to turn on this flag - see https://help.github.com/articles/dealing-with-line-endings), the headers generated from the .in files will have syntatic errors, causing compilation to fail.