v3.1.2 release notes

Signed-off-by: Cary Phillips <cary@ilm.com>

CHANGES.md

@@ -1,5 +1,6 @@
 # OpenEXR Release Notes
 
+* [Version 3.1.2](#version-312-september-30-2021) September 30, 2021
 * [Version 3.1.1](#version-311-august-2-2021) August 2, 2021
 * [Version 3.1.0](#version-310-july-22-2021) July 22, 2021
 * [Version 3.0.5](#version-305-july-1-2021) July 1, 2021
@@ -51,6 +52,63 @@
 * [Version 1.0.1](#version-101)
 * [Version 1.0](#version-10)
 
+## Version 3.1.2 (September 30, 2021)
+
+Patch release with various bug fixes, build improvements, and
+documentation updates.
+
+Specific OSS-fuzz issues:
+
+* OSS-fuzz [38912](https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=38912) Integer-overflow in Imf_3_1::bytesPerDeepLineTable
+* OSS-fuzz [39084](https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=39084) Divide-by-zero in Imf_3_1::RGBtoXYZ
+
+Merged Pull Requests:
+
+* [1153](https://github.com/AcademySoftwareFoundation/openexr/pull/1153)
+  Avoid div by zero with test for bad chromaticities in RGBtoXYZ
+* [1152](https://github.com/AcademySoftwareFoundation/openexr/pull/1152)
+  prevent overflow in bytesPerDeepLineTable 
+* [1151](https://github.com/AcademySoftwareFoundation/openexr/pull/1151)
+  Add additional text to ensure correct detection for threads 
+* [1147](https://github.com/AcademySoftwareFoundation/openexr/pull/1147)
+  Simplify the definition for bswap_32 for NetBSD 
+* [1142](https://github.com/AcademySoftwareFoundation/openexr/pull/1142)
+  Cleanup cmake thread detection 
+* [1141](https://github.com/AcademySoftwareFoundation/openexr/pull/1141)
+  Fix issue with unpacked size computation 
+* [1138](https://github.com/AcademySoftwareFoundation/openexr/pull/1138)
+  the HufDec struct used during decompression also contains a pointer 
+* [1136](https://github.com/AcademySoftwareFoundation/openexr/pull/1136)
+  Fixes #1135, test which assumed 64-bit pointer size 
+* [1134](https://github.com/AcademySoftwareFoundation/openexr/pull/1134)
+  Clean up enum declarations in OpenEXRCore 
+* [1133](https://github.com/AcademySoftwareFoundation/openexr/pull/1133)
+  Fix copy/paste error in special case unpack routine 
+* [1132](https://github.com/AcademySoftwareFoundation/openexr/pull/1132)
+  Build sphinx/doxygen docs with CMake 
+* [1131](https://github.com/AcademySoftwareFoundation/openexr/pull/1131)
+  Retire old docs 
+* [1130](https://github.com/AcademySoftwareFoundation/openexr/pull/1130)
+  Clean up OpenEXRCore doxygen comments 
+* [1129](https://github.com/AcademySoftwareFoundation/openexr/pull/1129)
+  Guard `__has_attribute` for compilers that don't support it 
+* [1124](https://github.com/AcademySoftwareFoundation/openexr/pull/1124)
+  Remove throw from ~IlmThread 
+* [1123](https://github.com/AcademySoftwareFoundation/openexr/pull/1123)
+  Require Imath 3.1 
+* [1122](https://github.com/AcademySoftwareFoundation/openexr/pull/1122)
+  Remove stray and unnecessary Imf:: namespace prefixes 
+* [1120](https://github.com/AcademySoftwareFoundation/openexr/pull/1120)
+  Docs: fixed wrong code examples in "how to read a file" section 
+* [1111](https://github.com/AcademySoftwareFoundation/openexr/pull/1111)
+  Fix document cross-references in .rst files and other gotchas 
+* [1108](https://github.com/AcademySoftwareFoundation/openexr/pull/1108)
+  Fix formatting in InterpretingDeepPixels.rst: 
+* [1104](https://github.com/AcademySoftwareFoundation/openexr/pull/1104)
+  'TheoryDeepPixels.rst' first pass converson from latex 
+* [1042](https://github.com/AcademySoftwareFoundation/openexr/pull/1042)
+  Fix broken link for releases 
+
 ## Version 3.1.1 (August 2, 2021)
 
 Patch release that fixes build failures on various systems, introduces