Don't fail the build if CPU model or memory can't be detected

This is purely informative anyhow and there is no reason to stop the
build just because this information couldn't be found (as happens when
running in s390x VM, for example).

Also avoid useless use of cat.

.travis.yml

@@ -495,7 +495,7 @@ matrix:
 before_install:
   - date -u
   - uname -a
-  - if test "$TRAVIS_OS_NAME" = "linux"; then lscpu && cat /proc/cpuinfo | grep "model name" && cat /proc/meminfo | grep MemTotal; fi
+  - if test "$TRAVIS_OS_NAME" = "linux"; then lscpu; grep "model name" /proc/cpuinfo || echo 'Unknown CPU model'; grep "MemTotal" /proc/meminfo || echo 'Unknown system memory amount'; fi
   - if test "$TRAVIS_OS_NAME" = "osx"; then sysctl -a | grep brand_string; fi
   # Travis overrides CC environment with compiler predefined values
   - if test -n "$GCC"; then export CC="gcc-$GCC" && export CXX="g++-$GCC"; fi