Add jobs for trusty (pretty close to RHEL 7)

.travis.yml.example-full

@@ -42,6 +42,14 @@ matrix:
   - env: BASE_BRANCH=7.0 EXTRA="CMD_CXXFLAGS=-std=c++11"
     compiler: clang
 
+# Trusty: compiler versions very close to RHEL 7
+
+  - env: BASE_BRANCH=7.0
+    dist: trusty
+
+  - env: BASE_BRANCH=7.0 EXTRA="CMD_CXXFLAGS=-std=c++11"
+    dist: trusty
+
 # Cross-compilation to Windows using MinGW and WINE
     
   - env: BASE_BRANCH=7.0 WINE=32 TEST=NO STATIC=YES
@@ -59,12 +67,10 @@ matrix:
 # Other gcc versions (adding as an extra package)
 
   - env: BASE_BRANCH=7.0
-    dist: xenial
 	compiler: gcc-6
 	addons: { apt: { packages: ["g++-6"], sources: ["ubuntu-toolchain-r-test"] } }
 
   - env: BASE_BRANCH=7.0
-    dist: xenial
 	compiler: gcc-7
 	addons: { apt: { packages: ["g++-7"], sources: ["ubuntu-toolchain-r-test"] } }