nim: unescape "\ " before splitting NIX_LDFLAGS

Ref #190126

pkgs/development/compilers/nim/nixbuild.patch

@@ -1,14 +1,3 @@
-commit 164ba50fc74b980f77047080b2ae1ea099ae9b27
-Author: Emery Hemingway <ehmry@posteo.net>
-Date:   Mon Sep 7 14:09:22 2020 +0200
-
-    Load libaries by absolute path on NixOS
-    
-    If "nixbuild" is defined then choose dynamic runtime libraries by
-    searching $NIX_LDFLAGS at compile-time.
-    
-    Fix #15194
-
 diff --git a/lib/pure/dynlib.nim b/lib/pure/dynlib.nim
 index f31ae94dd..debed9c07 100644
 --- a/lib/pure/dynlib.nim
@@ -37,7 +26,7 @@ index f31ae94dd..debed9c07 100644
 +    # to enable this behavior by default.
 +    #
 +    var libDirs = split(getEnv("LD_LIBRARY_PATH"), ':')
-+    for flag in split(getEnv("NIX_LDFLAGS")):
++    for flag in split(replace(getEnv("NIX_LDFLAGS"), "\\ ", " ")):
 +      if flag.startsWith("-L"):
 +        libDirs.add(flag[2..flag.high])
 +    for lib in dest: