* We must use the full path to the source file when calling MSVC so that debugging information shows up in the object files.
* Because of cygwin's use of /cygdrive when using full paths, we must use a cygwin-wrapper script in some cases to allow native win32 programs to use a fully qualified cygwin path.
* We have to call configure using the full path so that $(srcdir) contains the
full path in the Makefiles. The rules have been changed for win32 so that it
always use $(srcdir)/$*.{c,cpp} as the sourcefile name even when the file is in
the cwd. This works around both the /cygdrive issue and the msvc's path info
optimization.
* We still use the wrapper when calling rc.exe & nsinstall. nsinstall
frequently takes multiple args and is called all over the tree so changing each
calling site is going to be expensive. (I'll have to check the logs again but
I think the rc wrapping can go.)
* nspr & ldap still use the wrappers for all native win32 progs. Neither nspr
nor ldap uses the acoutput-fast.pl script to speed up the substitution of
@srcdir@ into their Makefiles so, makefile substitution will break if we use
dos-paths.
* In the handful of directories where we copy srcfiles from another directory
in lieu of using VPATHs, we have to now copy those files to $(srcdir) so that
the default rules can find them.
Bug #141834 r=leaf,wtc,dmose,mcs
