Add missing header installation block

This commit was SVN r333.

src/mca/lam/base/Makefile.am

@@ -16,3 +16,13 @@ headers = \
 
 libmca_lam_base_la_SOURCES = \
         mca_lam_param.c
+
+
+# Conditionally install the header files
+
+if WANT_INSTALL_HEADERS
+lamdir = $(includedir)/lam/mca/lam/base
+lam_HEADERS = $(headers)
+else
+lamdir = $(includedir)
+endif