libebl: Handle SYMTAB_SHNDX in ebl_dynamic_tag_name.

SYMTAB_SHNDX was introduced when elf.h was imported, but not yet handled
in ebl_dynamic_tag_name. Handle it and add an eu_static_assert to make
sure stdtags always contains DT_NUM entries.

https://sourceware.org/bugzilla/show_bug.cgi?id=22976

Signed-off-by: Mark Wielaard <mark@klomp.org>
diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index de325ab..b4e9049 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,9 @@
+2018-03-16  Mark Wielaard  <mark@klomp.org>
+
+	* ebldynamictagname.c (ebl_dynamic_tag_name): Add SYMTAB_SHNDX to
+	stdtags. Add a eu_static_assert to make sure stdtags contains all
+	DT_NUM entries.
+
 2018-02-21  Mark Wielaard  <mark@klomp.org>
 
 	* eblcheckreloctargettype.c (ebl_check_reloc_target_type): Accept