GDB Master Fails to Build on CentOS 7

Hi

This appears to be due to the older gcc apparently not defaulting to C99.
Either the code needs to change or -std=c99 needs to be passed by the build
machinery.

ibtool: compile:  gcc -O2 -g -pipe
-I/home/joel/rtems-work/rtems-source-builder/rtems/build/tmp/sb-1001/7/rtems-powerpc/home/joel/rtems-work/tools/7/include
-DHAVE_CONFIG_H -I. -I../../sourceware-mirror-binutils-gdb-ed29efb/opcodes
-I. -I../../sourceware-mirror-binutils-gdb-ed29efb/opcodes -I../bfd
-I../../sourceware-mirror-binutils-gdb-ed29efb/opcodes/../include
-I../../sourceware-mirror-binutils-gdb-ed29efb/opcodes/../bfd -W -Wall
-Wstrict-prototypes -Wmissing-prototypes -Wshadow -g -O2 -MT ppc-dis.lo -MD
-MP -MF .deps/ppc-dis.Tpo -c
../../sourceware-mirror-binutils-gdb-ed29efb/opcodes/ppc-dis.c -o ppc-dis.o
../../sourceware-mirror-binutils-gdb-ed29efb/opcodes/ppc-dis.c: In function
‘print_insn_powerpc’:
../../sourceware-mirror-binutils-gdb-ed29efb/opcodes/ppc-dis.c:1071:8:
error: ‘for’ loop initial declarations are only allowed in C99 mode
        for (int i = 0; i < 2; i++)

Thanks.

--joel
RTEMS