[Interest] Qt build system

[Carl Schumann]

Hi,

I am using Qt in an environment where there is already a build 
infrastructure in place.   Because of the amount of per-existing non-Qt 
code it is not feasible to build everything with qmake, e.g., because 
slot is actually a very common variable and argument name in our 
existing code base.

Therefore, I am trying to add Qt build support to our existing build 
system only for the programs that need it.   I would like to understand 
what the motivation is for the second command in the link rule of the 
qmake-generated Makefile please:
> $(TARGET):  $(OBJECTS)
> 	$(LINK) $(LFLAGS) -o $(TARGET) $(OBJECTS) $(OBJCOMP) $(LIBS)
> 	{ test -n "$(DESTDIR)" && DESTDIR="$(DESTDIR)" || DESTDIR=.; } && test $$(gdb --version | sed -e 's,[^0-9]\+\([0-9]\)\.\([0-9]\).*,\1\2,;q') -gt 72 && gdb --nx --batch --quiet -ex 'set confirm off' -ex "save gdb-index $$DESTDIR" -ex quit '$(TARGET)' && test -f $(TARGET).gdb-index && objcopy --add-section '.gdb_index=$(TARGET).gdb-index' --set-section-flags '.gdb_index=readonly' '$(TARGET)' '$(TARGET)' && rm -f $(TARGET).gdb-index || true

If it makes a difference this is Qt 4.8.4.

Thanks for your time.

Sincerely,
Carl Schumann