treewide: Use *Platform.extensions

pkgs/tools/networking/eggdrop/default.nix

@@ -1,9 +1,5 @@
 { stdenv, fetchFromGitHub, tcl }:
 
-let
-  shlib = if stdenv.isDarwin then "dylib" else "so";
-in
-
 stdenv.mkDerivation rec {
   name = "eggdrop-${version}";
   version = "1.6.21-nix1";
@@ -29,7 +25,7 @@ stdenv.mkDerivation rec {
   '';
 
   configureFlags = [
-    "--with-tcllib=${tcl}/lib/lib${tcl.libPrefix}.${shlib}"
+    "--with-tcllib=${tcl}/lib/lib${tcl.libPrefix}${stdenv.hostPlatform.extensions.sharedLibrary}"
     "--with-tclinc=${tcl}/include/tcl.h"
   ];
 

pkgs/tools/security/yara/default.nix

@@ -17,20 +17,16 @@ stdenv.mkDerivation rec {
 
   # FIXME: this is probably not the right way to make it work
   # make[2]: *** No rule to make target 'libyara/.libs/libyara.a', needed by 'yara'.  Stop.
-  dynamic_library_extension = ""
-    + stdenv.lib.optionalString stdenv.isLinux "so"
-    + stdenv.lib.optionalString stdenv.isDarwin "dylib"
-  ;
   prePatch = ''
     cat >staticlibrary.patch <<EOF
     --- a/Makefile.am 2015-11-01 11:39:12.000000000 +0100
     +++ b/Makefile.am 2015-11-01 11:45:32.000000000 +0100
     @@ -12 +12 @@
     -yara_LDADD = libyara/.libs/libyara.a
-    +yara_LDADD = libyara/.libs/libyara.${dynamic_library_extension}
+    +yara_LDADD = libyara/.libs/libyara${stdenv.hostPlatform.extensions.sharedLibrary}
     @@ -15 +15 @@
     -yarac_LDADD = libyara/.libs/libyara.a
-    +yarac_LDADD = libyara/.libs/libyara.${dynamic_library_extension}
+    +yarac_LDADD = libyara/.libs/libyara${stdenv.hostPlatform.extensions.sharedLibrary}
     EOF
   '';
   patches = [