package/boost: enable regex on host

regex is needed on host for host-riscv-isa-sim

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/boost/boost.mk

@@ -17,7 +17,7 @@ HOST_BOOST_FLAGS = --without-icu --with-toolset=gcc \
 	--without-libraries=$(subst $(space),$(comma),atomic chrono context \
 	contract container coroutine date_time exception fiber filesystem graph \
 	graph_parallel iostreams json locale log math mpi nowide program_options \
-	python random regex serialization stacktrace system test thread timer \
+	python random serialization stacktrace system test thread timer \
 	type_erasure wave)
 
 BOOST_WITHOUT_FLAGS += $(if $(BR2_PACKAGE_BOOST_ATOMIC),,atomic)