ExternalProject: avoid CMP0054 warnings

Found where ${command} is "make" which is a local variable.
Merge topic 'cmp0054-warnings-extproj' into next

a300d0ff ExternalProject: avoid CMP0054 warnings
ExternalProject: remove extra newlines from log messages

message() already adds a newline.
Merge topic 'extproj-extra-newlines' into next

480e6029 ExternalProject: remove extra newlines from log messages