Add exception for unicode_east_asian_fw_table.h to cpluspluscheck

unicode_east_asian_fw_table.h should not be compiled standalone, similarly
to unicode_combining_table.h, but cpluspluscheck did not get the memo.

Oversight in bab982161.

Per report from Tom Lane

src/tools/pginclude/cpluspluscheck

@@ -114,6 +114,7 @@ do
 
 	# Also not meant to be included standalone.
 	test "$f" = src/include/common/unicode_combining_table.h && continue
+	test "$f" = src/include/common/unicode_east_asian_fw_table.h && continue
 
 	# We can't make these Bison output files compilable standalone
 	# without using "%code require", which old Bison versions lack.