Fix cargo path and add CARGO_TARGET for cross compile (python#19)

There are still some issues with compilation, but those can be sorted out in a future PR.

Author: youknowone

Makefile.pre.in

@@ -61,6 +61,7 @@ DSYMUTIL_PATH=  @DSYMUTIL_PATH@
 CARGO_HOME=@CARGO_HOME@
 CARGO_TARGET_DIR=@CARGO_TARGET_DIR@
 CARGO_PROFILE=@CARGO_PROFILE@
+CARGO_TARGET=@CARGO_TARGET@
 
 GNULD=		@GNULD@
 
@@ -3373,7 +3374,7 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 # Module dependencies and platform-specific files
 
 cpython-sys: Modules/cpython-sys/Cargo.toml Modules/cpython-sys/build.rs Modules/cpython-sys/wrapper.h Modules/cpython-sys/parser.h
-	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) --manifest-path $(srcdir)/Cargo.toml
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) \$(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
 
 # force rebuild when header file or module build flavor (static/shared) is changed
 MODULE_DEPS_STATIC=Modules/config.c

Modules/makesetup

@@ -287,7 +287,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 			libs=
 			# depends on the headers through cpython-sys
 			rule="$objs: cpython-sys \$(srcdir)/Cargo.toml \$(srcdir)/Cargo.lock \$(srcdir)/$srcdir/$manifest $prefixed_srcs \$(PYTHON_HEADERS)"
-			rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) cargo build --lib --locked --package ${mods} --profile \$(CARGO_PROFILE) --manifest-path \$(srcdir)/Cargo.toml"
+			rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) \$(CARGO_HOME)/bin/cargo build --lib --locked --package ${mods} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
 			echo "$rule" >>$rulesf
 			for mod in $mods
 			do

configure

@@ -4328,10 +4328,20 @@ else
     CARGO_TARGET_DIR='debug'
     CARGO_PROFILE='dev'
   fi
+  # Set CARGO_TARGET for cross-compilation
+  case "$host" in
+    aarch64-apple-ios-simulator)
+      CARGO_TARGET="aarch64-apple-ios-sim"
+      ;;
+    *)
+      CARGO_TARGET="$host"
+      ;;
+  esac
 fi
 AC_SUBST([CARGO_HOME])
 AC_SUBST([CARGO_TARGET_DIR])
 AC_SUBST([CARGO_PROFILE])
+AC_SUBST([CARGO_TARGET])
 
 
 dnl detect sqlite3 from Emscripten emport