Fix building with -c dbg

Just create separate lists of flags (and corresponding features) for
each compilation mode, instead of trying to be cute with a default that
gets overriden.

Change-Id: Ib9741681030f5b88dcf200f0144156a626bc16aa
Signed-off-by: Brian Silverman <bsilver16384@gmail.com>
diff --git a/third_party/bazel-toolchain/toolchain/internal/configure.bzl b/third_party/bazel-toolchain/toolchain/internal/configure.bzl
index 6a183fc..2d8124d 100644
--- a/third_party/bazel-toolchain/toolchain/internal/configure.bzl
+++ b/third_party/bazel-toolchain/toolchain/internal/configure.bzl
@@ -131,6 +131,7 @@
         copts_dict = rctx.attr.copts,
         opt_copts_dict = rctx.attr.opt_copts,
         dbg_copts_dict = rctx.attr.dbg_copts,
+        fastbuild_copts_dict = rctx.attr.fastbuild_copts,
         linkopts_dict = rctx.attr.linkopts,
     )
     host_tools_info = dict([
@@ -282,6 +283,7 @@
     copts = toolchain_info.copts_dict.get(key, [])
     opt_copts = toolchain_info.opt_copts_dict.get(key, [])
     dbg_copts = toolchain_info.dbg_copts_dict.get(key, [])
+    fastbuild_copts = toolchain_info.fastbuild_copts_dict.get(key, [])
     linkopts = toolchain_info.linkopts_dict.get(key, [])
     target_toolchain_root = toolchain_info.toolchain_root
     if key in toolchain_info.target_toolchain_roots_dict:
@@ -319,6 +321,7 @@
     copts = {copts},
     opt_copts = {opt_copts},
     dbg_copts = {dbg_copts},
+    fastbuild_copts = {fastbuild_copts},
     linkopts = {linkopts},
 )
 
@@ -437,5 +440,6 @@
         copts = copts,
         opt_copts = opt_copts,
         dbg_copts = dbg_copts,
+        fastbuild_copts = fastbuild_copts,
         linkopts = linkopts,
     )