Document That uthash Development Files Are Now Required

Document that uthash Development Files are required after
the integration of #967.

Fixes #972.

Signed-off-by: Dan Anderson <daniel.anderson@intel.com>
diff --git a/INSTALL.md b/INSTALL.md
index 0831496..9091932 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -24,6 +24,7 @@
 * Code coverage analysis:
 * lcov
 * autoconf-archives
+* uthash development libraries and header files
 
 Most users will not need to install these dependencies.