git: fix darwin to linux cross-compilation (#348010)

pkgs/applications/version-management/git/default.nix

@@ -20,6 +20,7 @@
 , gzip # needed at runtime by gitweb.cgi
 , withSsh ? false
 , sysctl
+, deterministic-host-uname # trick Makefile into targeting the host platform when cross-compiling
 , doInstallCheck ? !stdenv.hostPlatform.isDarwin  # extremely slow on darwin
 , tests
 }:
@@ -84,7 +85,7 @@ stdenv.mkDerivation (finalAttrs: {
     done
   '';
 
-  nativeBuildInputs = [ gettext perlPackages.perl makeWrapper pkg-config ]
+  nativeBuildInputs = [ deterministic-host-uname gettext perlPackages.perl makeWrapper pkg-config ]
     ++ lib.optionals withManual [ asciidoc texinfo xmlto docbook2x
          docbook_xsl docbook_xml_dtd_45 libxslt ];
   buildInputs = [ curl openssl zlib expat cpio (if stdenv.hostPlatform.isFreeBSD then libiconvReal else libiconv) bash ]
@@ -130,8 +131,7 @@ stdenv.mkDerivation (finalAttrs: {
   # acceptable version.
   #
   # See https://github.com/Homebrew/homebrew-core/commit/dfa3ccf1e7d3901e371b5140b935839ba9d8b706
-  ++ lib.optional stdenv.hostPlatform.isDarwin "TKFRAMEWORK=/nonexistent"
-  ++ lib.optional (stdenv.hostPlatform.isFreeBSD && stdenv.hostPlatform != stdenv.buildPlatform) "uname_S=FreeBSD";
+  ++ lib.optional stdenv.hostPlatform.isDarwin "TKFRAMEWORK=/nonexistent";
 
   disallowedReferences = lib.optionals (stdenv.buildPlatform != stdenv.hostPlatform) [
     stdenv.shellPackage

pkgs/build-support/deterministic-uname/default.nix

@@ -31,7 +31,7 @@ substituteAll {
     then "GNU/Linux"
     else if forPlatform.isDarwin
     then "Darwin" # darwin isn't in host-os.m4 so where does this come from?
-    else if stdenv.buildPlatform.isFreeBSD
+    else if forPlatform.isFreeBSD
     then "FreeBSD"
     else "unknown";