gnu: curl: Add a search path for CURL_CA_BUNDLE.

* gnu/packages/curl.scm (curl)[native-search-paths]: New field.
* gnu/packages/image-viewers.scm (feh)[native-search-paths]: Inherit.

gnu/packages/curl.scm

@@ -66,6 +66,15 @@
        ("groff" ,groff)
        ("pkg-config" ,pkg-config)
        ("python" ,python-2)))
+   (native-search-paths
+    ;; Note: This search path is respected by the `curl` command-line tool only.
+    ;; Ideally we would bake this into libcurl itself so other users can benefit,
+    ;; but it's not supported upstream due to thread safety concerns.
+    (list (search-path-specification
+           (variable "CURL_CA_BUNDLE")
+           (file-type 'regular)
+           (separator #f)                         ;single entry
+           (files '("etc/ssl/certs/ca-certificates.crt")))))
    (arguments
     `(#:configure-flags '("--with-gnutls" "--with-gssapi")
       ;; Add a phase to patch '/bin/sh' occurances in tests/runtests.pl

gnu/packages/image-viewers.scm

@@ -83,11 +83,7 @@
     (native-search-paths
      ;; Feh allows overriding the libcurl builtin CA path (unset in Guix)
      ;; with the same variable as the `curl` command line HTTP tool.
-     (list (search-path-specification
-            (variable "CURL_CA_BUNDLE")
-            (file-type 'regular)
-            (separator #f)                         ;single entry
-            (files '("etc/ssl/certs/ca-certificates.crt")))))
+     (package-native-search-paths curl))
     (synopsis "Fast and light imlib2-based image viewer")
     (description
       "feh is an X11 image viewer aimed mostly at console users.