Merge bitcoin#32070: build: use make < 3.82 syntax for define directive

9157d9e build: use make < 3.82 syntax for define directive (Sjors Provoost)

Pull request description:

  From the GNU make 3.82 [release announcement](https://lists.gnu.org/archive/html/info-gnu/2010-07/msg00023.html) (2010):

  > The 'define' make directive now allows a variable assignment operator
    after the variable name, to allow for simple, conditional, or appending
    multi-line variable assignment.

  macOS ships with 3.81 (2006). This caused the multiprocess config options to be ignored.

  Fixes bitcoin#32068

ACKs for top commit:
  ryanofsky:
    Code review ACK 9157d9e. This is a pretty unusual bug and I don't understand how it wasn't causing any errors with make 3.81, just causing the flags to be ignored.

Tree-SHA512: a07322e25ef18296264379a2704f31c654df196d3ea09fe712885c38813e54d758a2d603ee9f7a302da8011fba6d139aa30a356175ca99df728ade2572a87560

Author: fanquake

depends/packages/capnp.mk

@@ -6,7 +6,7 @@ $(package)_file_name=$(native_$(package)_file_name)
 $(package)_sha256_hash=$(native_$(package)_sha256_hash)
 $(package)_patches=abi_placement_new.patch
 
-define $(package)_set_vars :=
+define $(package)_set_vars
   $(package)_config_opts := -DBUILD_TESTING=OFF
   $(package)_config_opts += -DWITH_OPENSSL=OFF
   $(package)_config_opts += -DWITH_ZLIB=OFF

depends/packages/libmultiprocess.mk

@@ -8,7 +8,7 @@ ifneq ($(host),$(build))
 $(package)_dependencies += native_capnp
 endif
 
-define $(package)_set_vars :=
+define $(package)_set_vars
 ifneq ($(host),$(build))
 $(package)_config_opts := -DCAPNP_EXECUTABLE="$$(native_capnp_prefixbin)/capnp"
 $(package)_config_opts += -DCAPNPC_CXX_EXECUTABLE="$$(native_capnp_prefixbin)/capnpc-c++"