Revert "bintools-wrapper: skip dynamic linker for static binaries"

This reverts commit ccfd26ef14.

These toolchain changes are too problematic, so reverting for now; see
https://github.com/NixOS/nixpkgs/pull/107086#issuecomment-749196366

pkgs/build-support/bintools-wrapper/add-flags.sh

@@ -3,7 +3,6 @@ var_templates_list=(
     NIX_IGNORE_LD_THROUGH_GCC
     NIX_LDFLAGS
     NIX_LDFLAGS_BEFORE
-    NIX_DYNAMIC_LINKER
     NIX_LDFLAGS_AFTER
     NIX_LDFLAGS_HARDEN
     NIX_HARDENING_ENABLE
@@ -26,10 +25,6 @@ if [ -e @out@/nix-support/libc-ldflags ]; then
     NIX_LDFLAGS_@suffixSalt@+=" $(< @out@/nix-support/libc-ldflags)"
 fi
 
-if [ -z "$NIX_DYNAMIC_LINKER_@suffixSalt@" ] && [ -e @out@/nix-support/dynamic-linker ]; then
-    NIX_DYNAMIC_LINKER_@suffixSalt@="$(< @out@/nix-support/dynamic-linker)"
-fi
-
 if [ -e @out@/nix-support/libc-ldflags-before ]; then
     NIX_LDFLAGS_BEFORE_@suffixSalt@="$(< @out@/nix-support/libc-ldflags-before) $NIX_LDFLAGS_BEFORE_@suffixSalt@"
 fi