gnu: emacs-telega: Test Emacs environment on startup.

Print a more helpful error message when someone attempts to run Telega on an
incompatible Emacs (e.g a 32-bit Emacs without wide ints).

* gnu/packages/patches/emacs-telega-test-env.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/emacs-xyz.scm (emacs-telega)[source]: Use it.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/local.mk

@@ -864,6 +864,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/emacs-magit-log-format-author-margin.patch	\
   %D%/packages/patches/emacs-scheme-complete-scheme-r5rs-info.patch	\
   %D%/packages/patches/emacs-source-date-epoch.patch		\
+  %D%/packages/patches/emacs-telega-test-env.patch		\
   %D%/packages/patches/emacs-undohist-ignored.patch	\
   %D%/packages/patches/emacs-wordnut-require-adaptive-wrap.patch	\
   %D%/packages/patches/emacs-zones-called-interactively.patch	\

gnu/packages/emacs-xyz.scm

@@ -21376,6 +21376,7 @@ (define-public emacs-telega
          (sha256
           (base32
            "0mv6i80958d9crzspzik5xh5g8326115bvg2frgv0dp9p6rm86m3"))
+         (patches (search-patches "emacs-telega-test-env.patch"))
          (file-name (git-file-name name version))))
       (build-system gnu-build-system)
       (arguments

gnu/packages/patches/emacs-telega-test-env.patch

@@ -0,0 +1,14 @@
+Test Emacs environment on startup.
+
+Patch by Diego N. Barbato
+
+--- a/telega.el	2020-02-07 17:07:18.549970090 +0100
++++ b/telega.el	2020-02-07 17:10:08.383499765 +0100
+@@ -82,6 +82,7 @@
+   "Start telegramming.
+ If prefix ARG is given, then will not pop to telega root buffer."
+   (interactive "P")
++  (telega-test-env t)
+   (telega--create-hier)
+ 
+   (unless (telega-server-live-p)