Fix build errors in with clang in gdb.compile/compile-cplus.c
Clang fails to compile the file, with the following error:
fatal error: 'iostream' file not found
This prevents the following testcase from executing:
gdb.compile/compile-cplus.exp
The testcase sets additional_flags when building with GCC, which
this commit causes to also be set when building with clang. This
makes the testcase fail to build with a different error:
warning: treating 'c' input as 'c++' when in C++ mode, this behavior
is deprecated [-Wdeprecated]
so this commit adds -Wno-deprecated in two places to sidestep this.
Note that, while allowing the testcase to build, this commit reveals
failures when the testsuite is built using clang.
gdb/testsuite/ChangeLog:
* gdb.compile/compile-cplus.exp (additional_flags): Also
set when building with clang.
(additional_flags, srcfilesoptions): Pass -Wno-deprecated
when building with clang.