allow building without help when lua interpreter is not available

fixes #10696

src/Makefile

-PKG_CONFIG ?= pkg-config
-LUAAPK ?= yes
-
+PKG_CONFIG		?= pkg-config
 LUA			?= $(firstword $(wildcard /usr/bin/lua5.3 /usr/bin/lua5.2))
 
+ifeq ($(LUA),no)
+LUAAPK			?= no
+else ifneq ($(LUA),)
+LUAAPK			?= yes
+else
+$(error Lua interpreter not found. Please specify LUA interpreter, or use LUA=no to build without help.)
+endif
+
 OPENSSL_CFLAGS		:= $(shell $(PKG_CONFIG) --cflags openssl)
 OPENSSL_LIBS		:= $(shell $(PKG_CONFIG) --libs openssl)
 
@@ -86,10 +92,14 @@ LIBS			:= -Wl,--as-needed \
 
 # Help generation
 quiet_cmd_genhelp = GENHELP $@
+ifneq ($(LUA),no)
       cmd_genhelp = $(LUA) $(src)/genhelp.lua $(filter %.scd, $^) > $@
+else
+      cmd_genhelp = echo \\\#define NO_HELP > $@
+endif
 
-$(obj)/help.h: $(src)/genhelp.lua $(wildcard doc/apk*.8.scd)
-	@$(call echo-cmd,genhelp) $(cmd_genhelp)
+$(obj)/help.h: $(src)/genhelp.lua $(wildcard doc/apk*.8.scd) FORCE
+	$(call if_changed,genhelp)
 
 CFLAGS_help.o		:= -I$(obj)
 

src/help.c

@@ -10,7 +10,7 @@
 #include "apk_applet.h"
 #include "apk_print.h"
 
-static int is_group(struct apk_applet *applet, const char *topic)
+static inline int is_group(struct apk_applet *applet, const char *topic)
 {
 	if (!applet) return strcasecmp(topic, "apk") == 0;
 	if (strcasecmp(topic, applet->name) == 0) return 1;
@@ -23,6 +23,7 @@ void apk_help(struct apk_applet *applet)
 {
 #include "help.h"
 
+#ifndef NO_HELP
 	char buf[uncompressed_help_size], *ptr, *msg;
 	unsigned long len = sizeof buf;
 	int num = 0;
@@ -38,4 +39,8 @@ void apk_help(struct apk_applet *applet)
 		}
 	}
 	if (num == 0) apk_error("Help not found");
+#else
+	fputc('\n', stdout);
+	apk_error("This apk-tools has been built without help");
+#endif
 }