Move headers into libbej folder

This change moves the libbej headers into its own libbej folder
(similar to libpldm) and install the headers under libbej directory.

Signed-off-by: Kasun Athukorala <kasunath@google.com>
Change-Id: I59ccb599bb042596a2d6bea620b83e3f8ce9f37d
diff --git a/meson.build b/meson.build
index bb7c166..d215d99 100644
--- a/meson.build
+++ b/meson.build
@@ -12,9 +12,9 @@
     'tests=' + (meson.is_subproject() ? 'disabled' : 'auto'),
   ])
 
-libbej_incs = include_directories('include')
+libbej_incs = include_directories('include/libbej')
 subdir('src')
-subdir('include')
+subdir('include/libbej')
 if not get_option('tests').disabled()
   subdir('test')
 endif