Add Travis jobs for non-hardened Rust

Right now we're having trouble getting Rust builds to succeed if
fragile hardening is enabled.  Add new mandatory jobs to make sure at
least some Rust testing happens in Travis.

Fixes bug 26449; bug not in any released tor.

.travis.yml

@@ -60,6 +60,7 @@ env:
   global:
     ## The Travis CI environment allows us two cores, so let's use both.
     - MAKEFLAGS="-j 2"
+    - HARDENING_OPTIONS="--enable-fragile-hardening"
   matrix:
     ## Leave at least one entry here or Travis seems to generate a
     ## matrix entry with empty matrix environment variables.  Leaving
@@ -109,6 +110,10 @@ matrix:
       env: DISTCHECK="yes" RUST_OPTIONS="--enable-rust --enable-cargo-online-mode"
     - compiler: gcc
       env: MODULES_OPTIONS="--disable-module-dirauth"
+    - compiler: gcc
+      env: HARDENING_OPTIONS="" RUST_OPTIONS="--enable-rust" TOR_RUST_DEPENDENCIES=true
+    - compiler: gcc
+      env: DISTCHECK="yes" HARDENING_OPTIONS="" RUST_OPTIONS="--enable-rust --enable-cargo-online-mode"
     ## The "sudo: required" forces non-containerized builds, working
     ## around a Travis CI environment issue: clang LeakAnalyzer fails
     ## because it requires ptrace and the containerized environment no
@@ -154,10 +159,10 @@ install:
 
 script:
   - ./autogen.sh
-  - ./configure $RUST_OPTIONS $COVERAGE_OPTIONS $MODULES_OPTIONS --disable-asciidoc --enable-fatal-warnings --disable-silent-rules --enable-fragile-hardening
+  - ./configure $RUST_OPTIONS $COVERAGE_OPTIONS $MODULES_OPTIONS --disable-asciidoc --enable-fatal-warnings --disable-silent-rules $HARDENING_OPTIONS
   ## We run `make check` because that's what https://jenkins.torproject.org does.
   - if [[ "$DISTCHECK" == "" ]]; then make check; fi
-  - if [[ "$DISTCHECK" != "" ]]; then make distcheck DISTCHECK_CONFIGURE_FLAGS="$RUST_OPTIONS $COVERAGE_OPTIONS --disable-asciidoc --enable-fatal-warnings --disable-silent-rules --enable-fragile-hardening"; fi
+  - if [[ "$DISTCHECK" != "" ]]; then make distcheck DISTCHECK_CONFIGURE_FLAGS="$RUST_OPTIONS $COVERAGE_OPTIONS --disable-asciidoc --enable-fatal-warnings --disable-silent-rules $HARDENING_OPTIONS"; fi
 
 after_failure:
   ## `make check` will leave a log file with more details of test failures.