This is seen in GHA Windows builds:

Building configuration 'windows-x64' (matching CONF_NAME=windows-x64)
Building configuration 'windows-x64' (matching CONF_NAME=windows-x64)
Building target 'default (product-bundles test-bundles)' in configuration 'windows-x64'
Compiling 8 files for BUILD_TOOLS_LANGTOOLS
Compiling 1 files for BUILD_TOOLS_HOTSPOT
Compiling 12 properties into resource bundles for jdk.jdeps
/usr/bin/bash: line 1: 950 Segmentation fault (core dumped) /usr/bin/make -s -r -R -I /cygdrive/d/a/jdk/jdk/jdk/make/common SPEC=/cygdrive/d/a/jdk/jdk/jdk/build/windows-x64/spec.gmk MAKE_LOG_FLAGS="-s" -f ModuleWrapper.gmk -I /cygdrive/d/a/jdk/jdk/jdk/make/common/modules -I/cygdrive/d/a/jdk/jdk/jdk/make/modules/java.base MODULE=java.base MAKEFILE_PREFIX=Copy
make[2]: *** [make/Main.gmk:157: java.base-copy] Error 139
make[2]: *** Waiting for unfinished jobs....

I am able to reproduce it in my local Windows VM, so this must be something in OpenJDK/Cygwin, rather than in GH infrastructure.

At this point I believe the recent Cygwin is broken. My machines have recently updated and started to fail. I downgraded "cygwin" and "cygwin-devel" packages, and the build works again. The last version that works is apparently 3.2.0. The first version that is broken is apparently 3.3.0. GHA always checks out the most recent Cygwin, which currently pulls {cygwin,cygwin-devel}:3.3.2.

The hypothesis that Cygwin is broken is also corroborated by sightings of the same failure in 17u and 11u forests, which do not have a lot of changes backported from mainline:
  https://github.com/shipilev/jdk17u/runs/4137529809?check_suite_focus=true
  https://github.com/shipilev/jdk11u-dev/runs/4136989053?check_suite_focus=true

Unfortunately, Cygwin setup does not allow (?) specifying package versions, which means it is hard to workaround.