gnu: Provide single-precision fftw library for pulseaudio

* gnu/packages/algebra.scm (fftwf): New variable
* gnu/packages/pulseaudio.scm (pulseaudio): Use it

gnu/packages/algebra.scm

@@ -27,7 +27,8 @@ (define-module (gnu packages algebra)
   #:use-module (guix licenses)
   #:use-module (guix packages)
   #:use-module (guix download)
-  #:use-module (guix build-system gnu))
+  #:use-module (guix build-system gnu)
+  #:use-module (guix utils))
 
 
 (define-public mpfrcx
@@ -231,3 +232,14 @@ (define-public fftw
 both real and complex data (as well as of even/odd data---i.e. the discrete
 cosine/ sine transforms or DCT/DST).")
     (license gpl2+)))
+
+(define-public fftwf
+  (package (inherit fftw)
+    (name "fftwf")
+    (arguments
+     (substitute-keyword-arguments (package-arguments fftw)
+       ((#:configure-flags cf)
+        `(cons "--enable-float" ,cf))))
+    (description
+     (string-append (package-description fftw)
+                    "  Single-precision version."))))

gnu/packages/pulseaudio.scm

@@ -168,7 +168,7 @@ (define pulseaudio
        ("pkg-config" ,pkg-config)
        ("m4" ,m4)
        ("libtool" ,libtool)
-       ("fftw" ,fftw)
+       ("fftwf" ,fftwf)
        ("avahi" ,avahi)
        ("check" ,check)))
     (propagated-inputs