Move the sensor utils into their own module

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I22f6a951921095660fd2be502e59a38161565a95
diff --git a/test/Makefile.am b/test/Makefile.am
index 3d74c88..0703f73 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -40,7 +40,7 @@
 sensor_host_unittest_LDADD = $(top_builddir)/sensors/host.o
 
 util_unittest_SOURCES = util_unittest.cpp
-util_unittest_LDADD = $(top_builddir)/util.o
+util_unittest_LDADD = $(top_builddir)/sensors/build_utils.o
 
 pid_zone_unittest_SOURCES = pid_zone_unittest.cpp
 pid_zone_unittest_LDADD = $(top_builddir)/pid/ec/pid.o \