build: only pass -optimized-tools to qt in debug mode

Qt's configure tells us that "-optimized-tools is not useful in -release
mode.", so don't use it there.

depends/packages/qt.mk

@@ -26,6 +26,7 @@ define $(package)_set_vars
 $(package)_config_opts_release = -release
 $(package)_config_opts_release += -silent
 $(package)_config_opts_debug = -debug
+$(package)_config_opts_debug += -optimized-tools
 $(package)_config_opts += -bindir $(build_prefix)/bin
 $(package)_config_opts += -c++std c++1z
 $(package)_config_opts += -confirm-license
@@ -67,7 +68,6 @@ $(package)_config_opts += -no-xinput2
 $(package)_config_opts += -nomake examples
 $(package)_config_opts += -nomake tests
 $(package)_config_opts += -opensource
-$(package)_config_opts += -optimized-tools
 $(package)_config_opts += -pkg-config
 $(package)_config_opts += -prefix $(host_prefix)
 $(package)_config_opts += -qt-libpng