Add "core.eol" config variable

Introduce a new configuration variable, "core.eol", that allows the user
to set which line endings to use for end-of-line-normalized files in the
working directory.  It defaults to "native", which means CRLF on Windows
and LF everywhere else.

Note that "core.autocrlf" overrides core.eol.  This means that

[core]
	autocrlf = true

puts CRLFs in the working directory even if core.eol is set to "lf".

Signed-off-by: Eyvind Bernhardsen <eyvind.bernhardsen@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Makefile b/Makefile
index 7bf2fca..bf5f8a7 100644
--- a/Makefile
+++ b/Makefile
@@ -214,6 +214,8 @@
 #   DEFAULT_EDITOR='~/bin/vi',
 #   DEFAULT_EDITOR='$GIT_FALLBACK_EDITOR',
 #   DEFAULT_EDITOR='"C:\Program Files\Vim\gvim.exe" --nofork'
+#
+# Define NATIVE_CRLF if your platform uses CRLF for line endings.
 
 GIT-VERSION-FILE: FORCE
 	@$(SHELL_PATH) ./GIT-VERSION-GEN
@@ -947,6 +949,7 @@
 	NO_CURL = YesPlease
 	NO_PYTHON = YesPlease
 	BLK_SHA1 = YesPlease
+	NATIVE_CRLF = YesPlease
 
 	CC = compat/vcbuild/scripts/clink.pl
 	AR = compat/vcbuild/scripts/lib.pl