CMake, .gitlab-ci.yml: try to cut down the output for Fedora RPM builds.

If the FORCE_CMAKE_NINJA_QUIET environment variable is set, have the
top-level CMakeLists.txt add the -q flag to the arguments to rpmbuild.
That appears to reduce the amount of output.

Set that environment varible in the rpm-fedora build.

.gitlab-ci.yml

@@ -164,7 +164,7 @@ build:rpm-fedora:
   script:
     # Shared GitLab runners limit the log size to 4M, so reduce verbosity. See
     # https://gitlab.com/gitlab-com/support-forum/issues/2790
-    - unset VERBOSE
+    - export FORCE_CMAKE_NINJA_QUIET=1
     - cmake3 -GNinja ..
     - ninja rpm-package
   needs:

CMakeLists.txt

@@ -3038,6 +3038,38 @@ if(RPMBUILD_EXECUTABLE)
 	if(CMAKE_VERBOSE_MAKEFILE)
 		list(APPEND _rpmbuild_with_args -v)
 	endif()
+	#
+	# This is ugly.
+	#
+	# At least some versions of rpmbuild define the cmake_build
+	# macro to run "cmake --build" with the "--verbose" option,
+	# with no obvious way to easily override that, so, if you
+	# are doing a build with lots of source files, and with
+	# lots of compiler options (for example, a log of -W flags),
+	# you can get a lot of output from rpmbuild.
+	#
+	# Wireshark is a program with lots of source files and
+	# lots of compiler options.
+	#
+	# GitLab's shared builders have a limit of 4MB on logs
+	# from build jobs.
+	#
+	# Wireshark uses the shared builders, and can produce
+	# more than 4MB with the Fedora RPM build; this causes
+	# the builds to fail.
+	#
+	# Adding the -q flag to rpmbuild appears to squelch
+	# most of the rpmbuild output.  This is not ideal,
+	# but it might at least let the builds succeed
+	# without failing due to hitting the log file limit.
+	#
+	# We don't add -q by default; if the build has
+	# the FORCE_CMAKE_NINJA_QUIET environment
+	# variable set, it will add it.
+	#
+	if(DEFINED ENV{FORCE_CMAKE_NINJA_QUIET})
+		list(APPEND _rpmbuild_with_args -q)
+	endif()
 	if(CMAKE_GENERATOR STREQUAL "Ninja")
 		list(APPEND _rpmbuild_with_args --with ninja)
 	endif()