libcap*: fix with multiple outputs

I don't think we need the license file in each of these,
so I only left it with the library (it isn't big).

pkgs/os-specific/linux/libcap/default.nix

@@ -19,6 +19,7 @@ stdenv.mkDerivation rec {
   makeFlags = "lib=lib prefix=$(out)";
 
   postInstall = ''
+    rm "$out"/lib/*.a
     mkdir -p "$dev/share/doc/${name}"
     cp ../License "$dev/share/doc/${name}/License"
   '';

pkgs/os-specific/linux/libcap/man.nix

@@ -10,6 +10,4 @@ stdenv.mkDerivation rec {
   makeFlags = "MANDIR=$(out)/share/man";
 
   preConfigure = "cd doc";
-
-  postInstall = libcap.postinst name;
 }

pkgs/os-specific/linux/libcap/pam.nix

@@ -12,6 +12,4 @@ stdenv.mkDerivation rec {
   preConfigure = "cd pam_cap";
 
   makeFlags = "${libcap.makeFlags} PAM_CAP=yes";
-
-  postInstall = libcap.postinst name;
 }

pkgs/os-specific/linux/libcap/progs.nix

@@ -21,5 +21,8 @@ stdenv.mkDerivation rec {
 
   installFlags = "RAISE_SETFCAP=no";
 
-  postInstall = libcap.postinst name;
+  postInstall = ''
+    mkdir -p "$out/share/doc/${name}"
+    cp ../License "$out/share/doc/${name}/"
+  '';
 }