Adding CI build for GNU/Linux

Plus some minor flags update (-g1) to fit the CI environment.
12 jobs for master in 7 minutes and 10 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Configure
passed #7670
linux
configure:linux

00:00:14

passed #7669
mac
configure:mac

00:00:14

passed #7668
windows
configure:win32

00:00:28

passed #7667
winxp
configure:winxp

00:00:30

 
  Build
passed #7674
linux
build:linux

00:01:44

passed #7673
mac
build:mac

00:05:34

passed #7672
windows
build:win32

00:02:30

passed #7671
winxp
build:winxp

00:02:20

 
  Dist
passed #7678
linux
dist:linux

00:00:05

passed #7677
mac
dist:mac

00:01:02

passed #7676
windows
dist:win32

00:00:22

passed #7675
winxp
dist:winxp

00:00:21