ERROR: can't build under arm64 architecture

[leslieluyu]

Describe the bug

when built on an AWS EC2 machine with Arm64 architecture, there was an error said:
-m arm64 is supported only when running on an ARM64 system.

To Reproduce

1. login to a aws ECS machine with arm64 platform
2. check the architecture

$uname -m
aarch64

4. follow the readme:

$ git clone https://github.com/GoogleCloudPlatform/cloud-profiler-java.git
$ cd cloud-profiler-java
$ ./build.sh -m arm64

5. error log:
   -m arm64 is supported only when running on an ARM64 system.

[leslieluyu]

already created a pr #49
please check it.