gnu: glib-networking: Use '/etc/ssl/certs/ca-certificates.crt' as TLS CA file.

* gnu/packages/gnome.scm (glib-networking)[arguments]: Pass
  '--with-ca-certificates=/etc/ssl/certs/ca-certificates.crt' to configure.
  Add 'disable-failing-tls-tests' phase.

gnu/packages/gnome.scm

@@ -1876,8 +1876,7 @@ library.")
     (build-system gnu-build-system)
     (arguments
      `(#:configure-flags
-       ;; FIXME: ca-certificates.crt is not available in the build environment.
+       '("--with-ca-certificates=/etc/ssl/certs/ca-certificates.crt")
-       '("--with-ca-certificates=no")
        #:phases
        (modify-phases %standard-phases
          (add-before 'configure 'patch-giomoduledir
@@ -1886,7 +1885,16 @@ library.")
                        (substitute* "configure"
                          (("GIO_MODULE_DIR=.*")
                           (string-append "GIO_MODULE_DIR=" %output
-                                         "/lib/gio/modules\n"))))))))
+                                         "/lib/gio/modules\n")))))
+         (add-before 'check 'disable-failing-tls-tests
+                     ;; The tests 'file-database' and 'connection' fail due to
+                     ;; missing ca-certificates.crt in the build environment.
+                     (lambda _
+                       (substitute* "tls/tests/Makefile"
+                         (("TESTS = \\$\\(am__EXEEXT_3\\)")
+                          (string-append
+                           "TESTS = certificate$(EXEEXT) "
+                           "$(am__EXEEXT_1) $(am__EXEEXT_2)"))))))))
     (native-inputs
      `(("pkg-config" ,pkg-config)
        ("intltool" ,intltool)))