osx: install completion scripts using install(1) to avoid umask badness

This actually fixes some tests that were showing us umask badness that
had been overlooked.

Makefile

@@ -165,14 +165,14 b' osx:'
 	make -C doc all install DESTDIR="$(PWD)/build/mercurial/"
         # install zsh completions - this location appears to be
         # searched by default as of macOS Sierra.
-	mkdir -p build/mercurial/usr/local/share/zsh/site-functions
-	cp contrib/zsh_completion build/mercurial/usr/local/share/zsh/site-functions/hg
+	install -d build/mercurial/usr/local/share/zsh/site-functions/
+	install -m 0644 contrib/zsh_completion build/mercurial/usr/local/share/zsh/site-functions/hg
         # install bash completions - there doesn't appear to be a
         # place that's searched by default for bash, so we'll follow
         # the lead of Apple's git install and just put it in a
         # location of our own.
-	mkdir -p build/mercurial/usr/local/hg/contrib
-	cp contrib/bash_completion build/mercurial/usr/local/hg/contrib/hg-completion.bash
+	install -d build/mercurial/usr/local/hg/contrib/
+	install -m 0644 contrib/bash_completion build/mercurial/usr/local/hg/contrib/hg-completion.bash
 	mkdir -p $${OUTPUTDIR:-dist}
 	HGVER=$$((cat build/mercurial/Library/Python/2.7/site-packages/mercurial/__version__.py; echo 'print(version)') | python) && \
 	OSXVER=$$(sw_vers -productVersion | cut -d. -f1,2) && \

tests/test-mac-packages.t

@@ -26,9 +26,9 b' Spot-check some randomly selected files:'
   ./Library/Python/2.7/site-packages/mercurial/pure/bdiff.pyc	100644	0/0
   ./Library/Python/2.7/site-packages/mercurial/pure/bdiff.pyo	100644	0/0
   $ grep zsh/site-functions/hg boms.txt | cut -d '	' -f 1,2,3
-  ./usr/local/share/zsh/site-functions/hg	100640	0/0
+  ./usr/local/share/zsh/site-functions/hg	100644	0/0
   $ grep hg-completion.bash boms.txt | cut -d '	' -f 1,2,3
-  ./usr/local/hg/contrib/hg-completion.bash	100640	0/0
+  ./usr/local/hg/contrib/hg-completion.bash	100644	0/0
   $ egrep 'man[15]' boms.txt | cut -d '	' -f 1,2,3
   ./usr/local/share/man/man1	40755	0/0
   ./usr/local/share/man/man1/hg.1	100644	0/0