targets/stm32f429i_disc1_stm32cube: Fix link errors

Adds a missing link deps to fix link errors when building for the
stm32f429i-disc1 target.

Change-Id: Ibacaf318ad679b2c3c0b4d28de3b73111bdbdf29
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/153890
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
Pigweed-Auto-Submit: Armando Montanez <amontanez@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/targets/stm32f429i_disc1_stm32cube/target_toolchains.gni b/targets/stm32f429i_disc1_stm32cube/target_toolchains.gni
index 269263b..6acf54e 100644
--- a/targets/stm32f429i_disc1_stm32cube/target_toolchains.gni
+++ b/targets/stm32f429i_disc1_stm32cube/target_toolchains.gni
@@ -90,6 +90,7 @@
   pw_build_LINK_DEPS = [
     "$dir_pw_assert:impl",
     "$dir_pw_log:impl",
+    "$dir_pw_toolchain/arm_gcc:arm_none_eabi_gcc_support",
   ]
 
   current_cpu = "arm"