Try to handle EINTR when writing data

Hopefully fixes issues such as this one:

heaptrack debug(2) [8859:8859]@5830 dlopen_notify_callback: /tmp/KDevelop-5.2.1-x86_64/usr/lib/libxcb-dri2.so.0 7fd27a93d000
heaptrack debug(1) [8885:8885]@5830 child_fork()
heaptrack debug(1) [8859:8859]@5831 write error 4/Interrupted system call
#1  0x00007fd298297f1e sp=0x00007ffe33957bd0 _ZN12_GLOBAL__N_19HeapTrack10writeErrorEv + 0x4c
#2  0x00007fd298297cff sp=0x00007ffe33957c00 _ZN12_GLOBAL__N_19HeapTrack24dl_iterate_phdr_callbackEP12dl_phdr_infomPv + 0x13c
#3  0x00007fd29123fc81 sp=0x00007ffe33957c50 dl_iterate_phdr + 0x171
#4  0x00007fd298297ec1 sp=0x00007ffe33957d00 _ZN12_GLOBAL__N_19HeapTrack17updateModuleCacheEv + 0xa5
#5  0x00007fd298297ae0 sp=0x00007ffe33957d20 _ZN12_GLOBAL__N_19HeapTrack12handleMallocEPvmRK5Trace + 0x54
#6  0x00007fd298298805 sp=0x00007ffe33957d60 heaptrack_malloc + 0xef
#7  0x00007fd298295f9b sp=0x00007ffe33957fb0 malloc + 0x5f
#8  0x00007fd291ab6089 sp=0x00007ffe33957fe0 _Znwm + 0x19
#9  0x00007fd29205cd42 sp=0x00007ffe33957ff0 _ZN7QObjectC1EPS_ + 0x22
#10 0x00007fd292023374 sp=0x00007ffe33958010 _ZN8QLibraryC2ERK7QStringP7QObject + 0x14
#11 0x00007fd292ef53d0 sp=0x00007ffe33958030 _ZN13KPluginLoader4loadEv + 0x60
#12 0x00007fd292ef54aa sp=0x00007ffe33958090 _ZN13KPluginLoader8instanceEv + 0xa
#13 0x00007fd292ef54ec sp=0x00007ffe339580a0 _ZN13KPluginLoader7factoryEv + 0x1c
#14 0x00007fd297d4eece sp=0x00007ffe33958140 _ZN8KDevelop16PluginController18loadPluginInternalERK7QString + 0x58e
#15 0x00007fd297d50396 sp=0x00007ffe339582a0 _ZN8KDevelop16PluginController10initializeEv + 0x8d6
#16 0x00007fd297d5ab85 sp=0x00007ffe339583f0 _ZN8KDevelop11CorePrivate10initializeENS_4Core5SetupERK7QString + 0xb95
#17 0x00007fd297d5c03d sp=0x00007ffe33958490 _ZN8KDevelop4Core10initializeENS0_5SetupERK7QString + 0x5d
#18 0x000000000040b472 sp=0x00007ffe339584c0 main + 0x5182
#19 0x00007fd29112ff4a sp=0x00007ffe339587d0 __libc_start_main + 0xea
#20 0x000000000040caed sp=0x00007ffe33958890 _start + 0x29
heaptrack debug(1) [8859:8859]@5858 shutdown()
heaptrack debug(1) [8859:8859]@5858 destroying LockedData
heaptrack debug(1) [8859:8859]@5858 done destroying LockedData
heaptrack debug(1) [8859:8859]@5885 shutdown() done

CCBUG: 393387