Enforce all text files to be checked out with LF-only line endings

Due to a switch to a redesigned Azure Pipeline that builds and publishes
our MINGW packages, the `git-extra` package is now built from a checkout
that uses the default `core.autoCRLF` setting of Git for Windows.

As a consequence, all files that were not marked explicitly with LF-only
line endings were changed to CR/LF line endings in the latest
`git-extra` package, including `git.nanorc` (and Nano does not like that
change, not one bit).

Let's just simplify the entire setup and tell Git that all text files
within `build-extra` are to have LF line endings.

This addresses git-for-windows/git#2429

Signed-off-by: Johannes Schindelin <[email protected]>

.gitattributes

@@ -1,25 +1,8 @@
-PKGBUILD eol=lf
-*.bat eol=lf
-*.c eol=lf
-*.cpp eol=lf
-*.css eol=lf
-*.install eol=lf
-*.install.in eol=lf
+* eol=lf
 *.iss eol=lf whitespace=tab-in-indent
-*.h eol=lf
-*.md eol=lf
-*.post eol=lf
-*.sh eol=lf
-*.txt eol=lf
-*.wxs eol=lf
 *.exe -text
 *.dll -text
 *.chm -text
 *.bmp -text
-/git-extra/astextplain eol=lf
-/git-extra/notepad eol=lf
-/git-extra/vi eol=lf
-/git-extra/vimrc eol=lf
-/git-extra/wordpad eol=lf
-/installer/InnoSetup/* eol=crlf
+*.ico -text
 /installer/InnoSetup/*.e32 -text