guix build: Add '--timeout' to the common build options.

* guix/scripts/build.scm (show-build-options-help): Document
  '--timeout'.
  (set-build-options-from-command-line): Pass #:timeout to
  'set-build-options'.
  (%standard-build-options): Add '--timeout'.
* doc/guix.texi (Invoking guix build): Document it.

doc/guix.texi

@@ -1903,6 +1903,13 @@ instead of offloading builds to remote machines.
 When the build or substitution process remains silent for more than
 @var{seconds}, terminate it and report a build failure.
 
+@item --timeout=@var{seconds}
+Likewise, when the build or substitution process lasts for more than
+@var{seconds}, terminate it and report a build failure.
+
+By default there is no timeout.  This behavior can be restored with
+@code{--timeout=0}.
+
 @item --verbosity=@var{level}
 Use the given verbosity level.  @var{level} must be an integer between 0
 and 5; higher means more verbose output.  Setting a level of 4 or more

guix/scripts/build.scm

@@ -126,6 +126,8 @@ options handled by 'set-build-options-from-command-line', and listed in
   (display (_ "
       --max-silent-time=SECONDS
                          mark the build as failed after SECONDS of silence"))
+  (display (_ "
+      --timeout=SECONDS  mark the build as failed after SECONDS of activity"))
   (display (_ "
       --verbosity=LEVEL  use the given verbosity LEVEL"))
   (display (_ "
@@ -142,6 +144,7 @@ options handled by 'set-build-options-from-command-line', and listed in
                      #:use-substitutes? (assoc-ref opts 'substitutes?)
                      #:use-build-hook? (assoc-ref opts 'build-hook?)
                      #:max-silent-time (assoc-ref opts 'max-silent-time)
+                     #:timeout (assoc-ref opts 'timeout)
                      #:verbosity (assoc-ref opts 'verbosity)))
 
 (define %standard-build-options
@@ -175,6 +178,11 @@ options handled by 'set-build-options-from-command-line', and listed in
                          (alist-cons 'max-silent-time (string->number* arg)
                                      result)
                          rest)))
+        (option '("timeout") #t #f
+                (lambda (opt name arg result . rest)
+                  (apply values
+                         (alist-cons 'timeout (string->number* arg) result)
+                         rest)))
         (option '("verbosity") #t #f
                 (lambda (opt name arg result . rest)
                   (let ((level (string->number arg)))