build: fix conditional

Automake conditional depth cannot use tab characters.

Tested: Verified the generated objects are now compiled by default.
Change-Id: I1de4cc74e9bf3380159dd07463b817bf460f81e0
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index 23f39bb..05e8ce9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,7 +3,7 @@
 sbin_PROGRAMS = swampd setsensor
 
 if !CONFIGURE_DBUS
-	BUILT_SOURCES = sensorlist-gen.cpp pidlist-gen.cpp zoneinfo-gen.cpp
+BUILT_SOURCES = sensorlist-gen.cpp pidlist-gen.cpp zoneinfo-gen.cpp
 endif
 CLEANFILES = $(BUILT_SOURCES)