filter: add lua support

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

cgit.mk

@@ -25,6 +25,25 @@ ifdef NO_C99_FORMAT
 	CFLAGS += -DNO_C99_FORMAT
 endif
 
+ifdef NO_LUA
+	CFLAGS += -DNO_LUA
+else
+
+ifeq (VANILLA,$(LUA_IMPLEMENTATION))
+	CFLAGS += -llua
+else
+	LUAJIT_LIBS := $(shell pkg-config --libs luajit)
+	LUAJIT_CFLAGS := $(shell pkg-config --cflags luajit)
+	CGIT_LIBS += $(LUAJIT_LIBS)
+	CFLAGS += $(LUAJIT_CFLAGS)
+endif
+
+endif
+
+CGIT_LIBS += -ldl
+
+
+
 CGIT_OBJ_NAMES += cgit.o
 CGIT_OBJ_NAMES += cache.o
 CGIT_OBJ_NAMES += cmd.o
@@ -61,9 +80,6 @@ $(CGIT_VERSION_OBJS): $(CGIT_PREFIX)VERSION
 $(CGIT_VERSION_OBJS): EXTRA_CPPFLAGS = \
 	-DCGIT_VERSION='"$(CGIT_VERSION)"'
 
-CGIT_LIBS += -ldl
-
-
 # Git handles dependencies using ":=" so dependencies in CGIT_OBJ are not
 # handled by that and we must handle them ourselves.
 cgit_dep_files := $(foreach f,$(CGIT_OBJS),$(dir $f).depend/$(notdir $f).d)