julia: remove redundant Nix-specific mtime patch

As far as I can tell this patch is redundant as all pre-compiled code
generated at build time is baked into the Julia system image and will
thus never get invalidated: Note that for both julia_10 and julia_15
there are no `.ji` files produced in the derivations.

pkgs/development/compilers/julia/1.0.nix

@@ -88,11 +88,6 @@ stdenv.mkDerivation rec {
   ;
 
   patches = [
-    # Julia recompiles a precompiled file if the mtime stored *in* the
-    # .ji file differs from the mtime of the .ji file.  This
-    # doesn't work in Nix because Nix changes the mtime of files in
-    # the Nix store to 1. So patch Julia to accept mtimes of 1.
-    ./allow_nix_mtime.patch
     ./diagonal-test.patch
     ./use-system-utf8proc-julia-1.0.patch
   ];

pkgs/development/compilers/julia/1.5.nix

@@ -34,12 +34,6 @@ stdenv.mkDerivation rec {
 
   patches = [
     ./use-system-utf8proc-julia-1.3.patch
-
-    # Julia recompiles a precompiled file if the mtime stored *in* the
-    # .ji file differs from the mtime of the .ji file.  This
-    # doesn't work in Nix because Nix changes the mtime of files in
-    # the Nix store to 1. So patch Julia to accept mtimes of 1.
-    ./allow_nix_mtime.patch
   ];
 
   postPatch = ''

pkgs/development/compilers/julia/allow_nix_mtime.patch

@@ -1,25 +0,0 @@
-From f79775378a9eeec5b99f18cc95735b12d172aba3 Mon Sep 17 00:00:00 2001
-From: Tom McLaughlin <pyro777@gmail.com>
-Date: Wed, 12 Dec 2018 13:01:32 -0800
-Subject: [PATCH] Patch to make work better with nix
-
----
- base/loading.jl | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/base/loading.jl b/base/loading.jl
-index 51201b98b6..b40c0690f6 100644
---- a/base/loading.jl
-+++ b/base/loading.jl
-@@ -1384,7 +1384,7 @@ function stale_cachefile(modpath::String, cachefile::String)
-                 # Issue #13606: compensate for Docker images rounding mtimes
-                 # Issue #20837: compensate for GlusterFS truncating mtimes to microseconds
-                 ftime = mtime(f)
--                if ftime != ftime_req && ftime != floor(ftime_req) && ftime != trunc(ftime_req, digits=6)
-+                if ftime != ftime_req && ftime != floor(ftime_req) && ftime != trunc(ftime_req, digits=6) && ftime != 1.0
-                     @debug "Rejecting stale cache file $cachefile (mtime $ftime_req) because file $f (mtime $ftime) has changed"
-                     return true
-                 end
--- 
-2.17.1
-