rename MIRI_TARGET -> MIRI_COMPILETEST_TARGET to clarify that this affects compiletest only

Author: RalfJung

tests/compiletest.rs

@@ -101,7 +101,7 @@ fn get_host() -> String {
 }
 
 fn get_target() -> String {
-    std::env::var("MIRI_TARGET").unwrap_or_else(|_| get_host())
+    std::env::var("MIRI_COMPILETEST_TARGET").unwrap_or_else(|_| get_host())
 }
 
 fn run_pass_miri(opt: bool) {

travis.sh

@@ -22,7 +22,7 @@ echo
 
 echo "Test miri with full MIR, on the host and other architectures"
 MIRI_SYSROOT="$MIRI_SYSROOT_BASE"/HOST cargo test --release --all-features
-MIRI_SYSROOT="$MIRI_SYSROOT_BASE" MIRI_TARGET="$FOREIGN_TARGET" cargo test --release --all-features
+MIRI_SYSROOT="$MIRI_SYSROOT_BASE" MIRI_COMPILETEST_TARGET="$FOREIGN_TARGET" cargo test --release --all-features
 echo
 
 echo "Test cargo integration"