Build: Fix circular object deps with old GCC

Build: Fix circular object deps with old GCC

When both -o and -MT are used, GCC 4.1 prints the object file twice in
the dependency file. e.g.:

foo.o foo.o: foo.c

If the file name is long, then the second occurrence moves to the next
line. e.g.:

ssl/statem/libssl-shlib-statem_dtls.o \
  ssl/statem/libssl-shlib-statem_dtls.o: ../ssl/statem/statem_dtls.c \

add-depends script scans one line at a time, so when the first line is
processed, the object file becomes a dependency itself.

Fix by removing -MT altogether.

This also fixes makedepend for nonstop platform.

Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25455)