Update microfactory compile error message to show the command that failed

Easier to debug than "Failed to compile: main: exit status 2"

Bug: 68770962
Test: sed -i 's/build.FindSources/files := build.FindSources/' build/soong/cmd/soong_ui/main.go \
      && m -j nothing

Change-Id: If78a4fa1c3999e7c658dce072c05d7d3e23b8683