buildGoModule: don't pass buildFlagsArray as file

Store buildFlagsArray as Bash global array variable instead of
creating/sourcing a file containing its declaration.

buildFlagsArray is short enough, and it is not assigned in a sub-shell.
There's no reason to pass it as a file. Storing it as a variable makes
the build more efficient.

pkgs/build-support/go/module.nix

@@ -218,8 +218,7 @@ let
       buildGoDir() {
         local cmd="$1" dir="$2"
 
-        . $TMPDIR/buildFlagsArray
-
+        declare -ga buildFlagsArray
         declare -a flags
         flags+=($buildFlags "''${buildFlagsArray[@]}")
         flags+=(''${tags:+-tags=''${tags// /,}})
@@ -258,11 +257,6 @@ let
         buildFlagsArray+=(-x)
       fi
 
-      if [ ''${#buildFlagsArray[@]} -ne 0 ]; then
-        declare -p buildFlagsArray > $TMPDIR/buildFlagsArray
-      else
-        touch $TMPDIR/buildFlagsArray
-      fi
       if [ -z "$enableParallelBuilding" ]; then
           export NIX_BUILD_CORES=1
       fi