package/netsurf: fix build with BR2_OPTIMIZE_FAST

Disable duktape with BR2_OPTIMIZE_FAST to fix the following build
failure:

In file included from content/handlers/javascript/duktape/duktape.h:195,
                 from build/Linux-framebuffer/duktape/application_cache.c:21:
content/handlers/javascript/duktape/duk_config.h:2861:2: error: #error __FAST_MATH__ defined, refusing to compile
 2861 | #error __FAST_MATH__ defined, refusing to compile
      |  ^~~~~

Fixes:
 - http://autobuild.buildroot.org/results/2f1b42e2be3aa76cbacd84f3d0ad8b13edce6982

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/netsurf/netsurf.mk

@@ -14,6 +14,17 @@ NETSURF_CPE_ID_VENDOR = netsurf-browser
 NETSURF_DEPENDENCIES = expat jpeg libpng \
 	host-bison host-flex host-gperf host-pkgconf host-vim
 
+# internal duktape doesn't build with BR2_OPTIMIZE_FAST
+ifeq ($(BR2_OPTIMIZE_FAST),y)
+define NETSURF_DUKTAPE_CONFIGURE_CMDS
+	echo "override NETSURF_USE_DUKTAPE := NO"       >> $(@D)/netsurf/Makefile.config
+endef
+else
+define NETSURF_DUKTAPE_CONFIGURE_CMDS
+	echo "override NETSURF_USE_DUKTAPE := YES"      >> $(@D)/netsurf/Makefile.config
+endef
+endif
+
 ifeq ($(BR2_PACKAGE_NETSURF_GTK),y)
 NETSURF_DEPENDENCIES += libgtk2
 NETSURF_FRONTEND = gtk2
@@ -77,6 +88,7 @@ endef
 endif
 
 define NETSURF_CONFIGURE_CMDS
+	$(NETSURF_DUKTAPE_CONFIGURE_CMDS)
 	$(NETSURF_ICONV_CONFIGURE_CMDS)
 	$(NETSURF_SVG_CONFIGURE_CMDS)
 	$(NETSURF_FONTLIB_CONFIGURE_CMDS)