fixup! release: add Mac OSX installer build

The v2.53.0-rc0.vfs.0.0 build began failing with:

    Undefined symbols for architecture arm64:
      "_iconv", referenced from:
          __libintl_find_msg in libintl.a[arm64][13](dcigettext.o)
      "_iconv_open", referenced from:
          __libintl_find_msg in libintl.a[arm64][13](dcigettext.o)
    ld: symbol(s) not found for architecture arm64

See https://github.com/microsoft/git/actions/runs/21450597958 for the
failing run. The previous release v2.52.0.vfs.0.5 built successfully on
January 24, 2026 (https://github.com/microsoft/git/actions/runs/21313971421).

The root cause is upstream commit cee341e ("macOS: use iconv from
Homebrew if needed and present", 2025-12-24), which was included in Git
v2.53.0-rc0 to work around an iconv bug in macOS 15.7.2. That commit
introduced USE_HOMEBREW_LIBICONV, which config.mak.uname now sets on
Darwin 24+, causing the Makefile to add Homebrew's libiconv to the
linker search path.

The problem is a symbol name mismatch: Homebrew's libiconv exports
symbols with a prefix (_libiconv, _libiconv_open) to avoid conflicting
with the system library, but Homebrew's gettext/libintl was built
against the system iconv which uses unprefixed symbols (_iconv,
_iconv_open). When building universal binaries, the linker finds
Homebrew's libiconv first and cannot resolve the symbols libintl needs.

The fix is to explicitly unset USE_HOMEBREW_LIBICONV and ICONVDIR in
config.mak, forcing the linker to use the system's /usr/lib/libiconv.dylib
which is already universal and exports the correct unprefixed symbols.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>

Author: dscho

.github/workflows/build-git-installers.yml

@@ -408,6 +408,9 @@ jobs:
           brew link --force gettext
 
           # Make universal gettext library
+          # Note: libintl depends on iconv, but we use the system's libiconv
+          # which is already universal, rather than Homebrew's libiconv which
+          # has different symbol names (_libiconv vs _iconv)
           lipo -create -output libintl.a /usr/local/opt/gettext/lib/libintl.a /opt/homebrew/opt/gettext/lib/libintl.a
 
       - name: Log in to Azure
@@ -487,9 +490,19 @@ jobs:
           # used in 'git version --build-options'.  We'll fix that in code.
           HOST_CPU = universal
           BASIC_CFLAGS += -arch arm64 -arch x86_64
+
+          # CRITICAL FIX: Disable USE_HOMEBREW_LIBICONV
+          # On Darwin 24+ (macOS 15), config.mak.uname sets USE_HOMEBREW_LIBICONV
+          # which causes ICONVDIR to point to Homebrew's libiconv. But Homebrew's
+          # libiconv exports _libiconv/_libiconv_open symbols (with prefix), while
+          # Homebrew's gettext/libintl was built against system iconv which uses
+          # _iconv/_iconv_open symbols (no prefix). We must use the system's
+          # /usr/lib/libiconv.dylib which is universal and has the correct symbols.
+          USE_HOMEBREW_LIBICONV =
+          ICONVDIR =
           EOF
 
-          # Configure the Git build to pick up gettext
+          # Configure the Git build to find our universal libintl.a
           homebrew_prefix="$(brew --prefix)"
           cat >>git/config.mak <<EOF
           CFLAGS = -I$homebrew_prefix/include -I/usr/local/opt/gettext/include