py/mkrules.mk: Remove unnecessary ; in makefile.
This ; make Windows compilation fail with GNU makefile 4.2.1.  It was added
in as part of a shell if-
statement, but this if-statement was subsequently removed in
so the semicolon is not needed.
@@ -72,7 +72,7 @@ $(OBJ): | $(HEADER_BUILD)/qstrdefs.generated.h $(HEADER_BUILD)/mpversion.h
# - else, process all source files ($^) [this covers "make -B" which can set $? to empty]
$(HEADER_BUILD)/qstr.i.last: $(SRC_QSTR) $(QSTR_GLOBAL_DEPENDENCIES) | $(HEADER_BUILD)/mpversion.h
$(ECHO) "GEN $@"
- $(Q)$(CPP) $(QSTR_GEN_EXTRA_CFLAGS) $(CFLAGS) $(if $(filter $?,$(QSTR_GLOBAL_DEPENDENCIES)),$^,$(if $?,$?,$^)) >$(HEADER_BUILD)/qstr.i.last;
+ $(Q)$(CPP) $(QSTR_GEN_EXTRA_CFLAGS) $(CFLAGS) $(if $(filter $?,$(QSTR_GLOBAL_DEPENDENCIES)),$^,$(if $?,$?,$^)) >$(HEADER_BUILD)/qstr.i.last
$(HEADER_BUILD)/qstr.split: $(HEADER_BUILD)/qstr.i.last
$(ECHO) "GEN $@"
