2,6,1: Cygwin fix: disabling binary stdin warning

#### Cygwin notes

##### Reported at

http://sourceware.org/bugzilla/show_bug.cgi?id=14598

##### Discussion

Fixing read mode compared to `patch-2.6.1-1.src.patch` (`sha1:3ca3f6b6f7c62ec54a54c5fcc5c3041dd1e4f129`).

Removing the `\r\n` → `\n` conversion.

The goal is to have the same behavior in Cygwin as in Linux.

Reasons to disable LF ↔ CRLF conversion by default

* It's off by default in Linux and script writers will sometimes not consider Cygwin compatibility.
* There are Windows editors that support LF newlines.
* The conversion is probably less commonly desired than not desired.

##### Test case

Previous version

	printf "a\r\n">a.txt && printf "\r\n">b.txt && diff -u a.txt b.txt>b.patch; patch --dry-run<b.patch
	Hunk #1 FAILED at 1.

This version

	printf "a\r\n">a.txt && printf "\r\n">b.txt && diff -u a.txt b.txt>b.patch; ./patch --dry-run<b.patch
	patching file a.txt

#####  Additional notes

Conversions done by text read and write

* `rt`		`\r\n` → `\n`
* `wt`		`\n` → `\r\n`

`t` in `rt`/`wt` is equivalent to `O_TEXT`