gnu: mawk: Remove generated file.

* gnu/packages/gawk.scm (mawk)[source]: Adjust snippet to remove
pre-generated file.
[arguments]: Don't build in parallel.
[native-inputs]: Add bison.

Change-Id: Ibc1c5128041a20a00ef6445f4e75ce1ff1e8bd97

gnu/packages/gawk.scm

@@ -25,6 +25,7 @@
   #:use-module (gnu packages)
   #:use-module (gnu packages base)
   #:use-module (gnu packages bash)
+  #:use-module (gnu packages bison)
   #:use-module (gnu packages gcc)
   #:use-module (gnu packages libsigsegv)
   #:use-module (gnu packages multiprecision)
@@ -148,11 +149,17 @@ block-scoped lexical variables."))))
               (modules '((guix build utils)))
               (snippet
                '(begin
+                  ;; Delete file generated by bison.
+                  (delete-file "parse.c")
                   ;; Prevent tests from hard coding PATH to a bogus value.
                   (substitute* '("test/mawktest" "test/fpe_test")
                     (("^PATH=.*")
                      ""))))))
     (build-system gnu-build-system)
+    (arguments
+     (list #:parallel-build? #f))   ; Prevent a race condition.
+    (native-inputs
+     (list bison))
     (synopsis "Text scanning and processing language")
     (description
      "@command{mawk} is an interpreter for the Awk programming language.