gnu: bitcoin-core: Make bitcoin-qt deterministic.

* gnu/packages/finance.scm (bitcoin-core)[arguments]<#:phases>
[make-qt-deterministic]: New phase.

Signed-off-by: Danny Milosavljevic <dannym@scratchpost.org>

gnu/packages/finance.scm

@@ -115,6 +115,11 @@
                          "/bin/lupdate"))
        #:phases
         (modify-phases %standard-phases
+          (add-before 'configure 'make-qt-deterministic
+           (lambda _
+            ;; Make Qt deterministic.
+            (setenv "QT_RCC_SOURCE_DATE_OVERRIDE" "1")
+            #t))
           (add-before 'check 'set-home
            (lambda _
             (setenv "HOME" (getenv "TMPDIR"))))))) ; Tests write to $HOME.