Add minimal support to `pkg-config imlib2`; imlib2-config has been
dropped since imlib2-1.7.5.

--- Makefile.orig	2021-11-19 07:48:49 UTC
+++ Makefile
@@ -1,8 +1,8 @@ O = telak.o fetch.o image.o parse.o toon.o
 VERSION = $(shell grep '^Version' ChangeLog | head -n 1 | cut -d' ' -f2 | tr -d ' ')
 BIN = telak
 O = telak.o fetch.o image.o parse.o toon.o
-LDFLAGS = $(shell imlib2-config --libs) $(shell curl-config --libs) -lgcrypt -lX11
-CFLAGS = -pg -W -Wall $(shell curl-config --cflags) $(shell imlib2-config --cflags) -DTELAK_USER_AGENT="\"$(BIN) $(VERSION)\"" -DTELAK_VERSION="\"$(VERSION)\"" -g
+LDFLAGS += $(shell pkg-config imlib2 --libs) $(shell curl-config --libs) -lgcrypt -lX11
+CFLAGS += -W -Wall $(shell curl-config --cflags) $(shell pkg-config imlib2 --cflags) -DTELAK_USER_AGENT="\"$(BIN) $(VERSION)\"" -DTELAK_VERSION="\"$(VERSION)\""
 
 BINDIR=$(DESTDIR)/usr/bin
 MANDIR=$(DESTDIR)/usr/share/man/man1