[][Remove old buggy uclibc++ support]

[Description]
Remove old buggy uclibc++ support

1. sync from OpenWRT trunk
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=6b2ed6101e4c97691ba3aa94f25895be536b3870

[Release-log]
N/A

Change-Id: Ifd1773b1cd9513dd7d0f8b0d5421d2f63de08fa6
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5208297
diff --git a/openwrt_patches-21.02/900-remove-uclibc-support.patch b/openwrt_patches-21.02/900-remove-uclibc-support.patch
new file mode 100755
index 0000000..c959d6e
--- /dev/null
+++ b/openwrt_patches-21.02/900-remove-uclibc-support.patch
@@ -0,0 +1,48 @@
+diff --git a/config/Config-build.in b/config/Config-build.in
+index 342859b..c72ba74 100644
+--- a/config/Config-build.in
++++ b/config/Config-build.in
+@@ -217,20 +217,6 @@ menu "Global build settings"
+ 		  make the system libraries incompatible with most of the packages that are
+ 		  not selected during the build process.
+ 
+-	choice
+-		prompt "Preferred standard C++ library"
+-		default USE_LIBSTDCXX if USE_GLIBC
+-		default USE_UCLIBCXX
+-		help
+-		  Select the preferred standard C++ library for all packages that support this.
+-
+-		config USE_UCLIBCXX
+-			bool "uClibc++"
+-
+-		config USE_LIBSTDCXX
+-			bool "libstdc++"
+-	endchoice
+-
+ 	comment "Hardening build options"
+ 
+ 	config PKG_CHECK_FORMAT_SECURITY
+diff --git a/include/uclibc++.mk b/include/uclibc++.mk
+index a1a61f2..10f8d98 100644
+--- a/include/uclibc++.mk
++++ b/include/uclibc++.mk
+@@ -1,16 +1,2 @@
+-ifndef DUMP
+-  ifdef __package_mk
+-    $(error uclibc++.mk must be included before package.mk)
+-  endif
+-endif
+-
+-PKG_PREPARED_DEPENDS += CONFIG_USE_UCLIBCXX
+-CXX_DEPENDS = +USE_UCLIBCXX:uclibcxx +USE_LIBSTDCXX:libstdcpp
+-
+-ifneq ($(CONFIG_USE_UCLIBCXX),)
+- ifneq ($(CONFIG_CCACHE),)
+-  TARGET_CXX_NOCACHE=g++-uc
+- else
+-  TARGET_CXX=g++-uc
+- endif
+-endif
++$(warn uclibc++.mk is deprecated. Please remove it and CXX_DEPENDS)
++CXX_DEPENDS = +libstdcpp