boost: Package Version Update -> 1.69.0

This package update provides one new library:
 -> Safe Numerics: A library for guaranteed correct integer arithmetic for
      C++14 and later, from Robert Ramey [1].

Discontinued Libraries
-> Signals (v1) is now removed. Its removal was announced in 1.68 and its
   deprecation was announced in 1.54. Boost 1.68 is the last release that
   provides this library. Users are encouraged to use Signals2 instead.
   The Boost community thanks Douglas Gregor for his work on Signals which
   served its users well and which also inspired Signals2 [2].

More info can be found at the usual place [3].

[1] : https://www.boost.org/doc/libs/1_69_0/libs/safe_numerics/doc/html/index.html
[2] : https://www.boost.org/doc/libs/1_69_0/doc/html/signals2.html
[3] : https://www.boost.org/users/history/version_1_69_0.html

Signed-off-by: Carlos Miguel Ferreira <carlosmf.pt@gmail.com>

libs/boost/Makefile

@@ -11,15 +11,15 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=boost
-PKG_VERSION:=1.68.0
-PKG_SOURCE_VERSION:=1_68_0
-PKG_RELEASE:=4
+PKG_VERSION:=1.69.0
+PKG_SOURCE_VERSION:=1_69_0
+PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)_$(PKG_SOURCE_VERSION).tar.bz2
 PKG_SOURCE_URL:=@SF/$(PKG_NAME)/$(PKG_NAME)/$(PKG_VERSION) https://dl.bintray.com/boostorg/release/$(PKG_VERSION)/source/
 PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)_$(PKG_SOURCE_VERSION)
 HOST_BUILD_DIR:=$(BUILD_DIR_HOST)/$(PKG_NAME)_$(PKG_SOURCE_VERSION)
-PKG_HASH:=7f6130bc3cf65f56a618888ce9d5ea704fa10b462be126ad053e80e553d6d8b7
+PKG_HASH:=8f32d4617390d1c2d16f26a27ab60d97807b35440d45891fa340fc2648b04406
 PKG_LICENSE:=Boost Software License <http://www.boost.org/users/license.html>
 PKG_MAINTAINER:=Carlos M. Ferreira <carlosmf.pt@gmail.com>
 
@@ -38,7 +38,7 @@ define Package/boost/Default
 endef
 
 define Package/boost/description
-This package provides the Boost v1.68.0 libraries.
+This package provides the Boost v1.69.0 libraries.
 Boost is a set of free, peer-reviewed, portable C++ source libraries.
 
 -----------------------------------------------------------------------------
@@ -76,7 +76,6 @@ This package provides the following run-time libraries:
  - random
  - regex
  - serialization and wserialization
- - signals
  - stackstrace
  - system
  - thread
@@ -85,7 +84,7 @@ This package provides the following run-time libraries:
  - wave
 
 There are many more header-only libraries supported by Boost.
-See more at http://www.boost.org/doc/libs/1_67_0/
+See more at http://www.boost.org/doc/libs/1_69_0/
 endef
 
 PKG_BUILD_DEPENDS:=boost/host PACKAGE_python:python PACKAGE_python3:python3
@@ -129,6 +128,35 @@ define Package/boost/config
 		depends on PACKAGE_boost
 		comment "Boost compilation options."
 
+		choice
+			prompt "Compile Visibility."
+				default boost-compile-visibility-hidden
+				help
+					Choose Boost symbols compilation visibility.
+					-> Global:
+						- a.k.a. "default" in gcc documentation. Global symbols are considered public,
+						 they are exported from shared libraries and can be redefined by another
+						 shared library or executable.
+					-> Protected:
+						- a.k.a. "symbolic". Protected symbols are exported from shared libraries but
+						 cannot be redefined by another shared library or executable. This mode is
+						 not supported on some platforms, for example OS X.
+					-> Hidden:
+						- Hidden symbols are not exported from shared libraries and cannot be 
+						 redefined by a different shared library or executable loaded in a process.
+						 In this mode, public symbols have to be explicitly marked in the source code
+						 to be exported from shared libraries. This is the recommended mode.
+
+			config boost-compile-visibility-global
+				bool "Global"
+			
+			config boost-compile-visibility-protected
+				bool "Protected"
+			
+			config boost-compile-visibility-hidden
+				bool "Hidden"
+		endchoice
+
 		choice
 			prompt "Compile Boost libraries."
 				default boost-static-and-shared-libs
@@ -326,7 +354,6 @@ $(eval $(call DefineBoostLibrary,random,system,))
 $(eval $(call DefineBoostLibrary,regex,,))
 $(eval $(call DefineBoostLibrary,serialization,,))
 $(eval $(call DefineBoostLibrary,wserialization,serialization,))
-$(eval $(call DefineBoostLibrary,signals,,))
 $(eval $(call DefineBoostLibrary,stacktrace,,))
 $(eval $(call DefineBoostLibrary,system,,))
 $(eval $(call DefineBoostLibrary,thread,system chrono atomic,))
@@ -374,6 +401,9 @@ define Build/Compile
 			--ignore-site-config \
 			--toolset=gcc-$(ARCH) abi=$(BOOST_ABI) \
 			--disable-long-double \
+			$(if $(CONFIG_boost-compile-visibility-global), visibility=global,) \
+			$(if $(CONFIG_boost-compile-visibility-protected), visibility=protected,) \
+			$(if $(CONFIG_boost-compile-visibility-hidden), visibility=hidden,) \
 			$(if $(CONFIG_boost-variant-release), variant=release,) \
 			$(if $(CONFIG_boost-variant-debug), variant=debug,) \
 			$(if $(CONFIG_boost-variant-profile), variant=profile,) \