Fix gdb-6.6 build with gcc-4.4.3

The problem is that gdb-6.6's Makefile enforces -Werror which turns
all compiler warnings in compilation errors.

It seems that gcc-4.4 introduced new compiler warnings that make the build fail,
so simply use -Wno-error to avoid the problem.

+ clear the build directory properly to avoid problems when using the
  same path for different builds.

Change-Id: I7d25215ae542b70e302ed546f3d4c6e616f5af27
1 file changed