Make playerctl support optional with a compiler flag

As Ubuntu doesn't provide `playerctl` by default, it's better to make
this optional.

Furthermore another build with playerctl support has been added to the
CI matrix.

.travis.yml

@@ -2,6 +2,26 @@ sudo: false
 dist: trusty
 matrix:
   include:
+    - script: make yabar
+      compiler: gcc
+      language: c
+      sudo: required
+      env: CPPFLAGS=-DOLD_LIBCONFIG PLAYERCTL=1
+      addons:
+        apt:
+          packages:
+            - libxcb-randr0-dev
+            - libconfig-dev
+            - libcairo2-dev
+            - libpango1.0-dev
+            - libxcb-ewmh-dev
+            - libxcb-icccm4-dev
+            - libasound2-dev
+            - libiw-dev
+            - wget
+      before_install:
+        - wget https://github.com/acrisci/playerctl/releases/download/v0.5.0/playerctl-0.5.0_amd64.deb -O playerctl.deb
+        - sudo dpkg -i playerctl.deb
     - script: make yabar
       compiler: gcc
       language: c

Makefile

@@ -3,8 +3,16 @@ CPPFLAGS += -DVERSION=\"$(VERSION)\" -D_POSIX_C_SOURCE=199309L -DYA_INTERNAL -DY
 			-DYA_ENV_VARS -DYA_INTERNAL_EWMH -DYA_ICON -DYA_NOWIN_COL -DYA_MUTEX -DYA_VAR_WIDTH \
 			-DYA_BSPWM
 CFLAGS += -std=c99 -Iinclude -pedantic -Wall -flto -O2 `pkg-config --cflags pango pangocairo libconfig gdk-pixbuf-2.0 alsa`
+
+DEPS += pango pangocairo libconfig gdk-pixbuf-2.0 alsa
+ifdef PLAYERCTL
+CFLAGS += -DPLAYERCTL
+CPPFLAGS += -DPLAYERCTL
+DEPS += playerctl-1.0
+endif
+
 LDFLAGS += -flto -O2
-LDLIBS += -liw -lxcb -lpthread -lxcb-randr -lxcb-ewmh -lxcb-icccm -lm `pkg-config --libs pango pangocairo libconfig gdk-pixbuf-2.0 alsa playerctl-1.0`
+LDLIBS += -liw -lxcb -lpthread -lxcb-randr -lxcb-ewmh -lxcb-icccm -lm `pkg-config --libs $(DEPS)`
 PROGRAM := yabar
 DOCS := $(PROGRAM).1
 PREFIX ?= /usr

src/intern_blks/ya_intern.c

@@ -22,10 +22,15 @@ void ya_int_battery(ya_block_t *blk);
 void ya_int_volume(ya_block_t *blk);
 void ya_int_wifi(ya_block_t *blk);
 void ya_int_diskspace(ya_block_t *blk);
+
+#ifdef PLAYERCTL
 void ya_int_song(ya_block_t *blk);
+#endif
 
 struct reserved_blk ya_reserved_blks[YA_INTERNAL_LEN] = {
+#ifdef PLAYERCTL
 	{"YABAR_SONG", ya_int_song},
+#endif
 	{"YABAR_DATE", ya_int_date},
 	{"YABAR_UPTIME", ya_int_uptime},
 	{"YABAR_THERMAL", ya_int_thermal},
@@ -131,6 +136,7 @@ __attribute__ ((gnu_inline)) inline void ya_setup_prefix_suffix(ya_block_t *blk,
 	}
 }
 
+#ifdef PLAYERCTL
 #include <playerctl/playerctl.h>
 #define CHECK_PLAYER_ERROR(PREFIX) \
 	if (PREFIX) \
@@ -190,6 +196,7 @@ void ya_int_song(ya_block_t *blk) {
 		sleep(blk->sleep);
 	}
 }
+#endif
 
 #include <time.h>
 void ya_int_date(ya_block_t * blk) {