gnu: gsl: Update to 2.6.

* gnu/packages/maths.scm (gsl): Update to 2.6.
[source]: Remove patch.
* gnu/packages/patches/gsl-test-i686.patch: Remove file.
* gnu/local.mk (dist_patch_DATA): Remove it.

gnu/local.mk

@@ -938,7 +938,6 @@ dist_patch_DATA =						\
   %D%/packages/patches/grep-timing-sensitive-test.patch		\
   %D%/packages/patches/groovy-add-exceptionutilsgenerator.patch	\
   %D%/packages/patches/grub-efi-fat-serial-number.patch		\
-  %D%/packages/patches/gsl-test-i686.patch			\
   %D%/packages/patches/gspell-dash-test.patch			\
   %D%/packages/patches/guile-1.8-cpp-4.5.patch			\
   %D%/packages/patches/guile-2.2-default-utf8.patch		\

gnu/packages/maths.scm

@@ -375,15 +375,14 @@ semiconductors.")
 (define-public gsl
   (package
     (name "gsl")
-    (version "2.5")
+    (version "2.6")
     (source (origin
               (method url-fetch)
               (uri (string-append "mirror://gnu/gsl/gsl-"
                                   version ".tar.gz"))
               (sha256
                (base32
-                "1395y9hlhqadn5g9j8q22224fds5sd92jxi9czfavjj24myasq04"))
-              (patches (search-patches "gsl-test-i686.patch"))))
+                "1a460zj9xmbgvcymkdhqh313c4l29mn9cffbi5vf33x3qygk70mp"))))
     (build-system gnu-build-system)
     (arguments
      `(;; Currently there are numerous tests that fail on "exotic"

gnu/packages/patches/gsl-test-i686.patch

@@ -1,17 +0,0 @@
-Work around a test failure due to a rounding issue on 32-bit
-platforms, as reported at:
-
-  https://lists.gnu.org/archive/html/bug-gsl/2016-10/msg00000.html
-
---- gsl-2.2.1/linalg/test.c	2016-10-05 13:27:42.464059730 +0200
-+++ gsl-2.2.1/linalg/test.c	2016-10-05 13:27:46.988095882 +0200
-@@ -4843,9 +4843,6 @@ main(void)
-   gsl_test(test_cholesky_decomp_unit(),  "Cholesky Decomposition [unit triangular]");
-   gsl_test(test_cholesky_solve(),        "Cholesky Solve");
- 
--  gsl_test(test_cholesky_decomp(r),      "Cholesky Decomposition");
--  gsl_test(test_cholesky_invert(r),      "Cholesky Inverse");
--  gsl_test(test_pcholesky_decomp(r),     "Pivoted Cholesky Decomposition");
-   gsl_test(test_pcholesky_solve(r),      "Pivoted Cholesky Solve");
-   gsl_test(test_pcholesky_invert(r),     "Pivoted Cholesky Inverse");
-   gsl_test(test_mcholesky_decomp(r),     "Modified Cholesky Decomposition");