Let r-2.15.2 build on Cygwin

[jpflori]

Although Cygwin supports long double, its libm lacks support for long double and r-2.15.2 needs logl.

We have three solutions:

• install back Cephe on Cygwin,
• backport r-3.0.0 support for --disable-long-double,
• only backport the part that replace logl by log.

I'll go for the third solution.

Use
http://boxen.math.washington.edu/home/jpflori/r-2.15.2.p1.spkg

CC: @dimpase @kcrisman

Component: porting: Cygwin

Keywords: cygwin spkg r

Author: Jean-Pierre Flori

Reviewer: Dmitrii Pasechnik

Merged: sage-5.7.beta4

Issue created by migration from https://trac.sagemath.org/ticket/14078

[jpflori]

Spkg diff, for review only.

[jpflori]

comment:1

Attachment: r-2.15.2.p1.diff.gz

[jpflori]

Description changed:

--- 
+++ 
@@ -6,3 +6,6 @@
 * only backport the part that replace logl by log.
 
 I'll go for the third solution.
+
+Use
+http://boxen.math.washington.edu/home/jpflori/r-2.15.2.p1.spkg

[jpflori]

Author: Jean-Pierre Flori

[dimpase]

comment:2

looks good.

[jdemeyer]

Reviewer: Dmitrii Pasechnik

[jdemeyer]

Merged: sage-5.7.beta4