PowerPC fix for gdb.server/sysroot.exp

PowerPC fix for gdb.server/sysroot.exp

On PowerPC, the stop in the printf function is of the form:

Breakpoint 2, 0x00007ffff7c6ab08 in printf@@GLIBC_2.17 () from /lib64/libc.so.6

On other architectures the output looks like:

Breakpoint 2, 0x0000007fb7ea29ac in printf () from /lib/aarch64-linux-gnu/libc.so.6

The following patch modifies the printf test by matchine any character
starting immediately after the printf.  The test now works for PowerPC
output as well as the output from other architectures.

The test has been run on a Power 10 system and and Intel x86_64 system.