Merge bitcoin/bitcoin#32568: depends: use "mkdir -p" when installing xproto

df9ebbf depends: use "mkdir -p" when installing xproto (fanquake)

Pull request description:

  It looks like the mkdir detection in xproto is broken on Alpine. Ensure we always use `mkdir -p`.

  Fixes #32494.

ACKs for top commit:
  hebasto:
    ACK df9ebbf, I have reviewed the code and it looks OK.
  janb84:
    ACK df9ebbf
  willcl-ark:
    ACK df9ebbf

Tree-SHA512: 0f23b1096ffdf5ffa13115665dc42b65835b78bb0ab04a8be8f210980356953ab518e1273302fe4c9239361201f4f9ac737c0ebf10625f4817f81b65b3b25572

Author: fanquake

depends/packages/xproto.mk

@@ -21,6 +21,8 @@ define $(package)_build_cmds
   $(MAKE)
 endef
 
+# mkdir detection is broken on Alpine. Set MKDIRPROG to ensure we always
+# use "mkdir -p", and avoid parallelism issues during install.
 define $(package)_stage_cmds
-  $(MAKE) DESTDIR=$($(package)_staging_dir) install
+  $(MAKE) MKDIRPROG="mkdir -p" DESTDIR=$($(package)_staging_dir) install
 endef