depends: Compile bdb with --disable-atomics when cross-compiling darwin

This sidesteps the problem where the atomics check tries to run a test
binary, which cannot be performed during cross compilation. We should
replace this with a better solution in future.

Part of #3710.

depends/packages/bdb.mk

@@ -10,6 +10,9 @@ $(package)_config_opts=--disable-shared --enable-cxx --disable-replication
 $(package)_config_opts_mingw32=--enable-mingw
 $(package)_config_opts_linux=--with-pic
 $(package)_config_opts_freebsd=--with-pic
+ifneq ($(build_os),darwin)
+$(package)_config_opts_darwin=--disable-atomicsupport
+endif
 $(package)_config_opts_aarch64=--disable-atomicsupport
 $(package)_cxxflags=-std=c++11
 endef