Export all constants for `linux_bionic`

They need to be referenced in adding a `linux_bionic` Bazel cc_toolchain

Test: CI
Bug: 205771732
Change-Id: I5469eac5559cdf76e02fdeccaf496e5ffcc1b08e
diff --git a/cc/config/arm64_linux_host.go b/cc/config/arm64_linux_host.go
index 2d316e6..9f5124b 100644
--- a/cc/config/arm64_linux_host.go
+++ b/cc/config/arm64_linux_host.go
@@ -58,8 +58,8 @@
 )
 
 func init() {
-	pctx.StaticVariable("LinuxBionicArm64Cflags", strings.Join(linuxCrossCflags, " "))
-	pctx.StaticVariable("LinuxBionicArm64Ldflags", strings.Join(linuxCrossLdflags, " "))
+	exportedVars.ExportStringListStaticVariable("LinuxBionicArm64Cflags", linuxCrossCflags)
+	exportedVars.ExportStringListStaticVariable("LinuxBionicArm64Ldflags", linuxCrossLdflags)
 }
 
 // toolchain config for ARM64 Linux CrossHost. Almost everything is the same as the ARM64 Android