initial buildroot for linux 5.15

package/gflags/Config.in

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+config BR2_PACKAGE_GFLAGS
+	bool "gflags"
+	depends on BR2_INSTALL_LIBSTDCPP
+	help
+	  The gflags package contains a C++ library that implements
+	  commandline flags processing. It includes built-in support for
+	  standard types such as string and the ability to define flags
+	  in the source file in which they are used.
+
+	  https://github.com/gflags/gflags
+
+comment "gflags needs a toolchain w/ C++"
+	depends on !BR2_INSTALL_LIBSTDCPP

package/gflags/gflags.hash

@@ -0,0 +1,5 @@
+# Locally computed
+sha256 34af2f15cf7367513b352bdcd2493ab14ce43692d2dcd9dfc499492966c64dcf gflags-2.2.2.tar.gz
+
+# Hash for license file:
+sha256 90d1f3701813c3cd65eee2dc736746fe46b465918f3f7d6d31463a2018b33fa5  COPYING.txt

package/gflags/gflags.mk

@@ -0,0 +1,22 @@
+################################################################################
+#
+# gflags
+#
+################################################################################
+
+GFLAGS_VERSION = 2.2.2
+GFLAGS_SITE = $(call github,gflags,gflags,v$(GFLAGS_VERSION))
+GFLAGS_INSTALL_STAGING = YES
+GFLAGS_LICENSE = BSD-3-Clause
+GFLAGS_LICENSE_FILES = COPYING.txt
+
+# Force Release otherwise libraries will be suffixed by _debug which will raise
+# unexpected build failures with packages that use gflags (e.g. rocksdb)
+GFLAGS_CONF_OPTS = -DCMAKE_BUILD_TYPE=Release
+
+ifeq ($(BR2_TOOLCHAIN_HAS_THREADS),)
+GFLAGS_CONF_OPTS += -DBUILD_gflags_LIB=OFF \
+	-DCMAKE_CXX_FLAGS="$(TARGET_CXXFLAGS) -DNO_THREADS"
+endif
+
+$(eval $(cmake-package))