My comment on this part of code is( from issue3871): 
+    # FIXME: next code is from issue870382
+    # MS C-runtime libraries never support backward compatibility.
+    # Linking to a different library without to specify correct runtime
+    # version for the headers will link renamed functions to msvcrt.
+    # See issue3308: this piece of code is python problem even
+    # with correct w32api headers.
+    # Issue: for MSVC compiler we can get the version and from version
+    # to determine mcvcrt as code below. But what about if python is
+    # build with GCC compiler?
+    # Output of sys.version is information for python build on first
+    # line, on the next line is information for the compiler and the
+    # output lack information for the C-runtime.

My vote is to remove function get_msvcr() from cygwinccompiler.py.