- LegacyKeyValueFormat: "ENV key=value" should be used
instead of legacy "ENV key value" format (line 42)
"""
The new format for declaring environment variables in Dockerfiles is ENV
key=value. This format, where the key and value are separated by an
equals sign (=), is the recommended approach. The older format, ENV key
value (with a space as a separator), is deprecated.
""" -- google search
For some reason, the default setting in all Toolchain.cmake
is:
```
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY BOTH)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE BOTH)
```
For cross-compilation, CMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER
makes sense (we only want to find executables in host system root),
but CMAKE_FIND_ROOT_PATH_MODE_LIBRARY/INCLUDE should be set
to ONLY, otherwise cmake may find libraries in host system root,
and try to link with incompatible libraries (instead of
cross-compilation sysroot).
Fixes#431.
