packages: Add '%hydra-supported-systems'.

* build-aux/hydra/gnu-system.scm (%hydra-supported-systems): Remove.
* guix/packages.scm (%hydra-supported-systems): New variable.

build-aux/hydra/gnu-system.scm

@@ -210,10 +210,6 @@ (define package->job
              #f)))))
 
 
-(define %hydra-supported-systems
-  ;; This is the list of system types for which build slaves are available.
-  '("x86_64-linux" "i686-linux" "mips64el-linux"))
-
 ;;;
 ;;; Hydra entry point.
 ;;;

guix/packages.scm

@@ -95,6 +95,7 @@ (define-module (guix packages)
             package-grafts
 
             %supported-systems
+            %hydra-supported-systems
             supported-package?
 
             &package-error
@@ -210,6 +211,11 @@ (define %supported-systems
   ;; expect all packages to build successfully here.
   '("x86_64-linux" "i686-linux" "armhf-linux" "mips64el-linux"))
 
+(define %hydra-supported-systems
+  ;; This is the list of system types for which build slaves are available.
+  (delete "armhf-linux" %supported-systems))
+
+
 ;; A package.
 (define-record-type* <package>
   package make-package