lnav: fix compilation

nix-env -i lnav currently result of a failure:

    command_executor.cc:34:21: fatal error: pcrecpp.h: No such file or
    directory

This fixes by using pcre-cpp instead of pcre.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

pkgs/tools/misc/lnav/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchFromGitHub, pcre, sqlite, ncurses,
+{ stdenv, fetchFromGitHub, pcre-cpp, sqlite, ncurses,
   readline, zlib, bzip2, autoconf, automake }:
 
 stdenv.mkDerivation rec {
@@ -19,7 +19,7 @@ stdenv.mkDerivation rec {
     zlib
     bzip2
     ncurses
-    pcre
+    pcre-cpp
     readline
     sqlite
   ];