PR# 2978 No warning is given about missing .def file when compiling system as dynamic library

I was trying to build a system (called vrt) as a dynamic library 
by specifying in the default section of the Ace file:

	shared_library_definition ("vrt.def")

I started building and the Eiffel compilation proceeded fine. The
C compilation also proceeded fine until it wanted to make edynlib.obj.
The console window of "finish_freezing.exe" then suddely complained:

NMAKE : fatal error U1073: don't know how to make 'E1\edynlib.c'
Stop.

The reason for this was that the file 'E1\edynlib.c' hadn't been 
created because the file 'vrt.def' didn't exist! However it took
some time before I realized that it was the missing .def file that
was the culprit, and it was very frustrating that EiffelStudio 
didn't simply tell me at degree 6 of freezing that it couldn't 
find the file 'vrt.def'!

1. Take any Eiffel system that compiles well as an executable.

2. Add the line "shared_library_definition (some_system.def)" 
to the system's Ace file, but don't create the file some_system.def.

3. Start freezing the system.