Call gen-fan-detect-defs script during build

Change-Id: Ie7b9109f097490401c2f4d75f278afad6926d18b
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/.gitignore b/.gitignore
index 8023943..5390726 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,4 +17,5 @@
 *.la

 *.lo

 *.o

+fan_detect_defs.cpp

 phosphor-fan-presence-tach