OSX needs to add librt in a funny way

Makefile.am

@@ -11,11 +11,17 @@ M_CPPFLAGS = -DSYSTEM_LIBINIPARSER=@SYSTEM_LIBINIPARSER@
 bin_PROGRAMS = cava
 cava_SOURCES = cava.c config.c input/common.c input/fifo.c input/shmem.c \
                output/terminal_noncurses.c output/raw.c
-cava_LDFLAGS = -L/usr/local/lib -Wl,-rpath /usr/local/lib -lrt
+cava_LDFLAGS = -L/usr/local/lib -Wl,-rpath /usr/local/lib
 cava_CPPFLAGS = -DPACKAGE=\"$(PACKAGE)\" -DVERSION=\"$(VERSION)\" \
            -D_POSIX_SOURCE -D _POSIX_C_SOURCE=200809L
 cava_CFLAGS = -std=c99 -Wall -Wextra -Wno-unused-result -Wno-maybe-uninitialized 
 
+if OSX
+    cava_CFLAGS += -DNORT
+else
+    cava_LDFLAGS += -lrt
+endif
+
 if ALSA
     cava_SOURCES += input/alsa.c
 endif

configure.ac

@@ -225,7 +225,31 @@ if test -z "$FONT_DIR" ; then
   FONT_DIR="$DEFAULT_FONT_DIR"
 fi
 
-
+AC_CANONICAL_HOST
+
+build_linux=no
+build_windows=no
+build_mac=no
+
+AC_MSG_NOTICE([Checking OS])
+# Detect the target system
+case "${host_os}" in
+    linux*)
+        AC_MSG_NOTICE([Linux detected])
+        build_linux=yes
+        ;;
+    darwin*)
+        AC_MSG_NOTICE([OSX detected])
+        build_mac=yes
+        ;;
+    *)
+        AC_MSG_ERROR(["OS $host_os is not supported"])
+        ;;
+esac
+
+# Pass the conditionals to automake
+AM_CONDITIONAL([LINUX], [test "$build_linux" = "yes"])
+AM_CONDITIONAL([OSX], [test "$build_mac" = "yes"])
 
 
 AC_CONFIG_FILES([Makefile])