rust: Switch to use RUST_XXX_SYS consistently

The code was using a mixture of XXX_SYS and RUST_XXX_SYS. Use
RUST_XXX_SYS consistently and add the variables to the global exclsion
on signatures as they're reflected in the directory triplets and trying
to filter them out the hashes separately is too painful.

(From OE-Core rev: ee0c0fdf9c1eba9eece6ed1293fda25bf18964b3)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/rust/rust.inc

@@ -79,7 +79,7 @@ python do_configure() {
     config = configparser.RawConfigParser()
 
     # [target.ARCH-poky-linux]
-    target_section = "target.{}".format(d.getVar('TARGET_SYS', True))
+    target_section = "target.{}".format(d.getVar('RUST_TARGET_SYS', True))
     config.add_section(target_section)
 
     llvm_config = d.expand("${YOCTO_ALTERNATE_EXE_PATH}")
@@ -128,11 +128,11 @@ python do_configure() {
     config.set("build", "vendor", e(True))
 
     if not "targets" in locals():
-        targets = [d.getVar("TARGET_SYS", True)]
+        targets = [d.getVar("RUST_TARGET_SYS", True)]
     config.set("build", "target", e(targets))
 
     if not "hosts" in locals():
-        hosts = [d.getVar("HOST_SYS", True)]
+        hosts = [d.getVar("RUST_HOST_SYS", True)]
     config.set("build", "host", e(hosts))
 
     # We can't use BUILD_SYS since that is something the rust snapshot knows
@@ -181,10 +181,10 @@ do_compile () {
 
 rust_do_install () {
     mkdir -p ${D}${bindir}
-    cp build/${HOST_SYS}/stage2/bin/* ${D}${bindir}
+    cp build/${RUST_HOST_SYS}/stage2/bin/* ${D}${bindir}
 
     mkdir -p ${D}${libdir}/rustlib
-    cp -pRd build/${HOST_SYS}/stage2/lib/* ${D}${libdir}
+    cp -pRd build/${RUST_HOST_SYS}/stage2/lib/* ${D}${libdir}
     # Remove absolute symlink so bitbake doesn't complain
     rm -f ${D}${libdir}/rustlib/src/rust
 }