kea: fix compilation with libcxx

Boost headers try to include experimental/string_view when std is less
than c++17. This does not work ith libcxx where this header is not
present.

Refreshed patches.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

net/kea/Makefile

@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=kea
 PKG_VERSION:=1.8.0
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://ftp.isc.org/isc/kea/$(PKG_VERSION)
@@ -178,7 +178,8 @@ CONFIGURE_VARS += \
 TARGET_CXXFLAGS += \
 	$(FPIC) \
 	-fdata-sections \
-	-ffunction-sections
+	-ffunction-sections \
+	-std=c++17
 
 TARGET_LDFLAGS += \
 	-Wl,--gc-sections,--as-needed

net/kea/patches/001-fix-cross-compile.patch

@@ -1,6 +1,8 @@
 --- a/configure.ac
 +++ b/configure.ac
-@@ -542,8 +542,8 @@ AC_TRY_COMPILE([
+@@ -580,10 +580,10 @@ AC_TRY_COMPILE([
+ 
+ usable_regex=
  AC_MSG_CHECKING(for usuable C++11 regex)
 -AC_TRY_RUN([
 +AC_TRY_COMPILE([

net/kea/patches/002-fix-host-compile.patch

@@ -1,6 +1,6 @@
 --- a/m4macros/ax_crypto.m4
 +++ b/m4macros/ax_crypto.m4
-@@ -454,7 +454,7 @@ EOF
+@@ -330,7 +330,7 @@ EOF
      dnl Check availability of SHA-2
      AC_MSG_CHECKING([support of SHA-2])
      LIBS_SAVED=${LIBS}

net/kea/patches/003-no-test-compile.patch

@@ -206,8 +206,8 @@
 -SUBDIRS = . testutils tests benchmarks
 +SUBDIRS = . benchmarks
  
- dhcp_data_dir = @localstatedir@/@PACKAGE@
+ # DATA_DIR is the directory where to put default CSV files and the DHCPv6
- kea_lfc_location = @prefix@/sbin/kea-lfc
+ # server ID file (i.e. the file where the server finds its DUID at startup).
 --- a/src/lib/dns/Makefile.am
 +++ b/src/lib/dns/Makefile.am
 @@ -1,6 +1,6 @@