boost: make fiber module select the context module

The boost fiber module uses the boost context module, so it should
select it.

Due to this, the boost fiber module inherits the dependencies of boost
context: it needs exception_ptr handling, and is only available on the
architectures where boost context is supported.

Fixes:

  http://autobuild.buildroot.net/results/56509d315defb95d4ac6e278a9d40cd98f61baa7

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[Thomas: use only one comment for both gcc bug dependencies.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/boost/Config.in

@@ -124,19 +124,24 @@ config BR2_PACKAGE_BOOST_EXCEPTION
 
 config BR2_PACKAGE_BOOST_FIBER
 	bool "boost-fiber"
+	depends on BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL
 	# mips support uses the "pause" instruction, only available
 	# since mips32r2/mips64r2.
 	depends on !BR2_MIPS_CPU_MIPS32 && !BR2_MIPS_CPU_MIPS64
+	depends on !BR2_TOOLCHAIN_HAS_GCC_BUG_64735 # boost-context
 	depends on !BR2_TOOLCHAIN_HAS_GCC_BUG_85180
+	select BR2_PACKAGE_BOOST_CONTEXT
 	help
 	  C++11 userland threads library.
 
 comment "boost-fiber needs a toolchain w/ NPTL"
+	depends on BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS
 	depends on !BR2_TOOLCHAIN_HAS_THREADS_NPTL
 
-comment "boost-fiber needs a toolchain not affected by GCC bug 85180"
-	depends on BR2_TOOLCHAIN_HAS_GCC_BUG_85180
+comment "boost-fiber needs a toolchain not affected by GCC bug 64735, 85180"
+	depends on BR2_PACKAGE_BOOST_CONTEXT_ARCH_SUPPORTS
+	depends on BR2_TOOLCHAIN_HAS_GCC_BUG_64735 || BR2_TOOLCHAIN_HAS_GCC_BUG_85180
 
 config BR2_PACKAGE_BOOST_FILESYSTEM
 	bool "boost-filesystem"