fftw3: improved to build/install a shared library as well

multimedia/fftw3/fftw3.conf

@@ -2,6 +2,7 @@
 # This copyright note is auto-generated by ./scripts/Create-CopyPatch.
 #
 # Filename: package/.../fftw3/fftw3.conf
+# Copyright (C) 2011 The OpenSDE Project
 # Copyright (C) 2004 - 2006 The T2 SDE Project
 #
 # More information can be found in the files COPYING and README.
@@ -12,6 +13,9 @@
 # GNU General Public License can be found in the file COPYING.
 # --- SDE-COPYRIGHT-NOTE-END ---
 
+# shared library support has to be enabled explicitely
+[ "$SDECFG_STATIC" != 1 ] && var_append extraconfopt " " "--enable-shared"
+
 # Optimization
 [ "$arch" = "x86" ] && var_append confopt " " "--enable-i386-hacks"