mingw: do not let ld strip relocations

This is the first step for enabling ASLR (Address Space Layout Randomization) support. We want to enable ASLR for better protection against exploiting security holes in Git: it makes it harder to attack software by making code addresses unpredictable. The problem fixed by this commit is that `ld.exe` seems to be stripping relocations which in turn will break ASLR support. We just make sure it's not stripping the main executable entry. Signed-off-by: İsmail Dönmez <ismail@i10z.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>