gnu: fftgen: Improve style.

* gnu/packages/fpga.scm (fftgen)[arguments]: Use G-Expressions.

Change-Id: I024bb0fc490682209cf28d49110f7585e4906e16
Signed-off-by: Andreas Enge <andreas@enge.fr>

gnu/packages/fpga.scm

@@ -826,7 +826,8 @@ and @file{.h} files.")
     (package
       (name "fftgen")
       (version (git-version "0" revision commit))
-      (source (origin
+      (source
+       (origin
          (method git-fetch)
          (uri (git-reference
                 (url "https://github.com/ZipCPU/dblclockfft")
@@ -837,15 +838,16 @@ and @file{.h} files.")
            "1rvln871wjkbbqnv88jnx328xlhn5sgbr8fglk3ajnd9rwgiq3jg"))))
       (build-system gnu-build-system)
       (arguments
-       `(#:test-target "bench-test"
-         #:make-flags '("CFLAGS=-g -O2")          ;default flags lack -O2
-         #:phases (modify-phases %standard-phases
+       (list
+        #:test-target "bench-test"
+        #:make-flags #~(list "CFLAGS=-g -O2") ;default flags lack -O2
+        #:phases
+        #~(modify-phases %standard-phases
             (delete 'configure)
             (replace 'install
-                      (lambda* (#:key outputs #:allow-other-keys)
-                        (let ((bin (string-append (assoc-ref outputs "out")
-                                                  "/bin")))
-                          (install-file "sw/fftgen" bin)))))))
+              (lambda _
+                (install-file "sw/fftgen"
+                              (string-append #$output "/bin")))))))
       (native-inputs (list bc fftw python-minimal verilator which))
       (synopsis "Generic pipelined FFT core generator")
       (description "fftgen produces @acronym{FFT, fast-Fourier transforms}