Bug#19738 "make install" tries to build files that "make" should already have built

- Move gen_lex_hash to EXTRA_PROGRAMS


sql/Makefile.am:
  Move gen_lex_hash to EXTRA_PROGRAMS, this will make it be built only when lex_hash.h need to be rebuilt

sql/Makefile.am

@@ -27,7 +27,7 @@ INCLUDES =		@ZLIB_INCLUDES@ \
 WRAPLIBS=		@WRAPLIBS@
 SUBDIRS =		share
 libexec_PROGRAMS =	mysqld
-noinst_PROGRAMS =	gen_lex_hash
+EXTRA_PROGRAMS =	gen_lex_hash
 bin_PROGRAMS =		mysql_tzinfo_to_sql
 gen_lex_hash_LDFLAGS =  @NOINST_LDFLAGS@
 LDADD =			$(top_builddir)/myisam/libmyisam.a \