[toolchain][prebuilt] add prebuilt gcc stamps for aarch64 linux machines

Change-Id: I2612c1b4cc2fecab619e06d9a257363be7308118
diff --git a/prebuilt/versions/toolchain/aarch64-elf/Linux-aarch64/version.sha b/prebuilt/versions/toolchain/aarch64-elf/Linux-aarch64/version.sha
new file mode 100644
index 0000000..2f889ba
--- /dev/null
+++ b/prebuilt/versions/toolchain/aarch64-elf/Linux-aarch64/version.sha
@@ -0,0 +1 @@
+509cd48809f5252ffc8ef0c72dbf208151750f66
diff --git a/prebuilt/versions/toolchain/x86_64-elf/Linux-aarch64/version.sha b/prebuilt/versions/toolchain/x86_64-elf/Linux-aarch64/version.sha
new file mode 100644
index 0000000..2f889ba
--- /dev/null
+++ b/prebuilt/versions/toolchain/x86_64-elf/Linux-aarch64/version.sha
@@ -0,0 +1 @@
+509cd48809f5252ffc8ef0c72dbf208151750f66