package/gpsd: remove -std=gnu++98 from CFLAGS

In 2016 buildroot commit b4c050e9af added
-std=gnu++98 also to CFLAGS knowing that it will cause warnings:

https://lists.nongnu.org/archive/html/gpsd-dev/2016-09/msg00082.html
'Although this leads to lots of warnings on every compilation with gcc:
"cc1: warning: command line option '-std=gnu++98' is valid for C++/ObjC++ but not for C"'

These warnings are still present but cause a misdetection in configure

    Checking if strerror_r() returns int... no

because here warnings are treated as errors, quoting config.log:

cc1: error: command-line option ‘-std=gnu++98’ is valid for C++/ObjC++ but not for C [-Werror]
cc1: all warnings being treated as errors

In 2017 upstream committed
d287c76f4f
which added "std::" namespace prefixes and fixed the original problem.

-std=gnu++98 being removed from CFLAGS lets configure correctly detect
strerror_r():

    Checking if strerror_r() returns int... yes

and no new build errors occur:

                             arm-aarch64 [ 1/35]: OK
                   bootlin-aarch64-glibc [ 2/35]: OK
               bootlin-arcle-hs38-uclibc [ 3/35]: OK
                    bootlin-armv5-uclibc [ 4/35]: OK
                     bootlin-armv7-glibc [ 5/35]: OK
                   bootlin-armv7m-uclibc [ 6/35]: SKIPPED
                      bootlin-armv7-musl [ 7/35]: OK
                bootlin-m68k-5208-uclibc [ 8/35]: SKIPPED
               bootlin-m68k-68040-uclibc [ 9/35]: OK
             bootlin-microblazeel-uclibc [10/35]: OK
                bootlin-mipsel32r6-glibc [11/35]: OK
                   bootlin-mipsel-uclibc [12/35]: OK
                 bootlin-openrisc-uclibc [13/35]: OK
        bootlin-powerpc64le-power8-glibc [14/35]: OK
           bootlin-powerpc-e500mc-uclibc [15/35]: OK
                   bootlin-riscv32-glibc [16/35]: OK
                   bootlin-riscv64-glibc [17/35]: OK
                    bootlin-riscv64-musl [18/35]: OK
                 bootlin-s390x-z13-glibc [19/35]: OK
                      bootlin-sh4-uclibc [20/35]: OK
                   bootlin-sparc64-glibc [21/35]: OK
                    bootlin-sparc-uclibc [22/35]: OK
                    bootlin-x86-64-glibc [23/35]: OK
                     bootlin-x86-64-musl [24/35]: OK
                   bootlin-x86-64-uclibc [25/35]: OK
                   bootlin-x86-i686-musl [26/35]: OK
                   bootlin-xtensa-uclibc [27/35]: OK
                            br-arm-basic [28/35]: SKIPPED
                    br-arm-full-nothread [29/35]: SKIPPED
                      br-arm-full-static [30/35]: SKIPPED
                   br-i386-pentium4-full [31/35]: FAILED
                      br-mips64-n64-full [32/35]: OK
                 br-mips64r6-el-hf-glibc [33/35]: OK
               br-powerpc-603e-basic-cpp [34/35]: SKIPPED
               br-powerpc64-power7-glibc [35/35]: OK
35 builds, 6 skipped, 1 build failed, 0 legal-info failed, 0 show-info failed

The br-i386-pentium4-full error is not caused by gpsd:

package/python3/python3.mk:324: *** Python3 doesn't work with uClibc and
kernel headers < 5.1. Please use a different toolchain or unselect
Python3..

Fixes:
https://autobuild.buildroot.org/results/52d747d33d714ea10b9e7ee10adeadd9e4512c2d/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Tested-by: Yann E. MORIN <yann.morin@orange.com>
Reviewed-by: Yann E. MORIN <yann.morin@orange.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit f0023ca18d)
Signed-off-by: Thomas Perale <thomas.perale@mind.be>

package/gpsd/gpsd.mk

@@ -37,7 +37,6 @@ endif
 # Build libgpsmm if we've got C++
 ifeq ($(BR2_INSTALL_LIBSTDCPP),y)
 GPSD_LDFLAGS += -lstdc++
-GPSD_CFLAGS += -std=gnu++98
 GPSD_CXXFLAGS += -std=gnu++98
 GPSD_SCONS_OPTS += libgpsmm=yes
 else