[release] Boost 1.76.0 Release Candidate 12

From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2021-04-13 21:11:00

The second release candidates for the 1.76.0 release are now available at:
<https://boostorg.jfrog.io/artifactory/main/release/1.76.0/source/ <https://dl.bintray.com/boostorg/release/1.76.0/source/>>

The SHA256 checksums are as follows:

7bd7ddceec1a1dfdcbdb3e609b60d01739c38390a5f956385a12f3122049f0ca  boost_1_76_0_rc2.tar.gz
0fd43bb53580ca54afc7221683dfe8c6e3855b351cd6dce53b1a24a7d7fbeedd  boost_1_76_0_rc2.zip
88782714f8701b6965f3fce087a66a1262601dd5ccd5b2e5305021beb53042a1  boost_1_76_0_rc2.7z
f0397ba6e982c4450f27bf32a2a83292aba035b827a5623a14636ea583318c41  boost_1_76_0_rc2.tar.bz2

Changes from RC1:
* A missing include was added to a Boost.Regex header. This fixes compilation on gcc 11.

As always, the release managers would appreciate it if you download the
candidate of your choice and give building it a try. Please report both
success and failure, and anything else that is noteworthy.

-- The Release managers