build: enable AM_INIT_AUTOMAKE([subdir-objects])

Squelches (justified) warnings with automake 1.14.

Object files are built in subdirectories now so fix up the dtrace
postprocessing step to scan for *.lo files in said subdirectories.

Fixes #866.

.gitignore

@@ -14,6 +14,7 @@ vgcore.*
 /aclocal.m4
 /ar-lib
 /autom4te.cache/
+/compile
 /config.guess
 /config.log
 /config.status

Makefile.am

@@ -215,7 +215,7 @@ src/unix/uv-dtrace.o: src/unix/uv-dtrace.d ${libuv_la_OBJECTS}
 # every created .o, most projects don't need to include more than one .d
 .d.o:
 	$(AM_V_GEN)$(DTRACE) $(DTRACEFLAGS) -G -o $(top_builddir)/uv-dtrace.o -s $< \
-		`grep '^pic_object' ${top_builddir}/*.lo | cut -f 2 -d\'`
+		`grep '^pic_object' $$(find ${top_builddir} -name "*.lo") | cut -f 2 -d\'`
 	$(AM_V_GEN)printf %s\\n \
 		'# ${top_builddir}/uv-dtrace.lo - a libtool object file' \
 		'# Generated by libtool (GNU libtool) 2.4' \

configure.ac

@@ -14,12 +14,13 @@
 
 AC_PREREQ(2.57)
 AC_INIT([libuv], [0.11.5], [https://github.com/joyent/libuv/issues])
-AM_INIT_AUTOMAKE([foreign -Wall -Werror])
+AM_INIT_AUTOMAKE([foreign subdir-objects -Wall -Werror])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CANONICAL_HOST
 AC_ENABLE_SHARED
 AC_ENABLE_STATIC
 AC_PROG_CC
+AM_PROG_CC_C_O
 # AM_PROG_AR is not available in automake v0.11 but it's essential in v0.12.
 m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])