It seems the license header was omitted when dfp.m4 was originally
contributed in 2010 (commit 3c39bca6bb, r0-102573 or svn r163815.
This copies the license from libdecnumber/configure.ac since dfp.m4
was originally extracted from that file.
2022-04-29 Christophe Lyon <christophe.lyon@arm.com>
config/
* dfp.m4: Add license header.