Travis: Enable additional sanitizer tests

- Re-purpose the non-SIMD test to test with MSan as well.
- Re-purpose the ASan test to test with UBSan as well.
- Use the default Travis build environment rather than specifying Ubuntu
  14.04.  I think I added 'dist: trusty' back when 14.04 was newer than
  the default, but now it's older than the default.
- Enable verbose output for any unit tests that fail (so we can see the
  sanitizer output.)
diff --git a/.travis.yml b/.travis.yml
index 4bbe022..35a7907 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,41 +16,47 @@
       env: BUILD_OFFICIAL=1
       osx_image: xcode8.3
     - os: linux
-      dist: trusty
       compiler: clang
       env:
         CMAKE_BUILD_TYPE=RelWithDebInfo
-        CFLAGS_RELWITHDEBINFO="-O1 -g -fsanitize=address -fno-omit-frame-pointer"
+        CFLAGS_RELWITHDEBINFO="-O1 -g -fsanitize=address,undefined -fno-omit-frame-pointer"
         CMAKE_FLAGS="-DENABLE_SHARED=0"
         ASAN_OPTIONS="detect_leaks=1 symbolize=1"
+        CTEST_OUTPUT_ON_FAILURE=1
       addons:
         apt:
           packages:
             - nasm
     - os: linux
-      dist: trusty
       compiler: gcc
-      env: CMAKE_FLAGS="-DWITH_12BIT=1"
+      env:
+        CMAKE_FLAGS="-DWITH_12BIT=1"
+        CTEST_OUTPUT_ON_FAILURE=1
     - os: linux
-      dist: trusty
       compiler: gcc
-      env: CMAKE_FLAGS="-DWITH_JPEG7=1"
+      env:
+        CMAKE_FLAGS="-DWITH_JPEG7=1"
+        CTEST_OUTPUT_ON_FAILURE=1
       addons:
         apt:
           packages:
             - nasm
     - os: linux
-      dist: trusty
       compiler: gcc
-      env: CMAKE_FLAGS="-DWITH_JPEG8=1"
+      env:
+        CMAKE_FLAGS="-DWITH_JPEG8=1"
+        CTEST_OUTPUT_ON_FAILURE=1
       addons:
         apt:
           packages:
             - nasm
     - os: linux
-      dist: trusty
-      compiler: gcc
-      env: CMAKE_FLAGS="-DWITH_SIMD=0"
+      compiler: clang
+      env:
+        CMAKE_BUILD_TYPE=RelWithDebInfo
+        CFLAGS_RELWITHDEBINFO="-O3 -g -fsanitize=memory -fPIE"
+        CMAKE_FLAGS="-DWITH_SIMD=0"
+        CTEST_OUTPUT_ON_FAILURE=1
 
 addons:
   homebrew: