Hexagon compilation on MacOS system

[apeskov]

Short desc
This changes allow my to compile and tune models for hexagon directly from my macOS laptop without full switching to linux environment.

List of changes

• Replace local linker call with call from docker container with Hexagon SDK. Yes, that is the only SDK tool used by TVM during compilation.
• Enhanced search of ADB. Not only in PATH, but also in ANDROID_HOME, ANDROID_SDK_ROOT and default sdk installation directory. Mac OS doesn't allow to easily change default PATH env var for UI application launched from dock bar. So adb is not available for IDE by default.

Motivation
Some engineers would like to continue work with comfortable macOS environment even if they have to play with hexagon devices. At this moment there is no official Hexagon SDK for macOS system. Alternatives are next: fully switch to remote linux, use local linux virtual machine or try to introduce required hexagon SDK functionality for macOS. The last option is more preferable to me.

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[kparzysz-quic]

Could you either merge this code into tools.py or rename this file to tools_macos.py?

[apeskov]

Sure, as you wish. File name "tools_macos.py" doesn't look like perfect match with content, so I moved it to "tools.py".

[FdyCN]

Short desc This changes allow my to compile and tune models for hexagon directly from my macOS laptop without full switching to linux environment.

List of changes

• Replace local linker call with call from docker container with Hexagon SDK. Yes, that is the only SDK tool used by TVM during compilation.
• Enhanced search of ADB. Not only in PATH, but also in ANDROID_HOME, ANDROID_SDK_ROOT and default sdk installation directory. Mac OS doesn't allow to easily change default PATH env var for UI application launched from dock bar. So adb is not available for IDE by default.

Motivation Some engineers would like to continue work with comfortable macOS environment even if they have to play with hexagon devices. At this moment there is no official Hexagon SDK for macOS system. Alternatives are next: fully switch to remote linux, use local linux virtual machine or try to introduce required hexagon SDK functionality for macOS. The last option is more preferable to me.

@apeskov Is there any ReadME.md to follow？I am a newbee in Hexagon, and i don't know how to use them. thanks a lot.