Use default jobs number when compiling boost

According to current boost docs, not specifying -j parameter will default to using all cores to compile,
so removing these should speed up compiling boost. This code dates back to 2014 when the default
may have been a single core, so it was specified.

depends/packages/boost.mk

@@ -38,16 +38,16 @@ endef
 
 ifeq ($(host_os),linux)
 define $(package)_build_cmds
-  ./b2 -d2 -j2 -d1 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) cxxflags=-std=c++11 stage
+  ./b2 -d2 -d1 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) cxxflags=-std=c++11 stage
 endef
 define $(package)_stage_cmds
-  ./b2 -d0 -j4 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) cxxflags=-std=c++11 install
+  ./b2 -d0 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) cxxflags=-std=c++11 install
 endef
 else
 define $(package)_build_cmds
-  ./b2 -d2 -j2 -d1 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) stage
+  ./b2 -d2 -d1 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) stage
 endef
 define $(package)_stage_cmds
-  ./b2 -d0 -j4 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) install
+  ./b2 -d0 --prefix=$($(package)_staging_prefix_dir) $($(package)_config_opts) install
 endef
 endif