NuttX: define LD to point to GNU ld, NuttX provided LD points to GCC wrapper now .

NuttX: define LD to point to GNU ld, NuttX provided LD points to GCC wrapper now .

The use of GCC wrapper and collect2 can have advantages
for LTO, whole program optimization C++ templates,
but causes many problems. Many low level linker options
has to be escaped by -Wl, and -nostartfiles -nodefaultlibs
has to be added to modules and ELF programs linking etc.

Signed-off-by: Pavel Pisa <ppisa@pikron.com>