gspawn: Handle EINTR in a few more cases
gspawn: Handle EINTR in a few more cases

I was debugging gthread/tests/spawn-multithreaded.c, and while I
don't think I actually hit EINTR in any of these cases, it'd be
good to fix them anyways.

https://bugzilla.gnome.org/show_bug.cgi?id=652072

cosimoc/glib,cention-sany/glib,johne53/MB3Glib,antono/glib,cention-sany/glib,darren-clark/android_platform_external_bluetooth_glib,krichter722/glib,bluez-android/glib,justinkb/aosp-bluez.glib,endlessm/glib,Distrotech/glib,01org/android-bluez-glib,Distrotech/glib,justinkb/aosp-bluez.glib,tchakabam/glib,mzabaluev/glib,ieei/glib,mzabaluev/glib,zsx/glib,pstglia/external-bluetooth-glib,tchakabam/glib,tamaskenez/glib,justinkb/aosp-bluez.glib,johne53/MB3Glib,tamaskenez/glib,antono/glib,pstglia/platform-external-bluetooth-glib,lukasz-skalski/glib,ieei/glib,pstglia/external-bluetooth-glib,djdeath/glib,endlessm/glib,bluez-android/glib,djdeath/glib,lukasz-skalski/glib,tamaskenez/glib,cention-sany/glib,darren-clark/android_platform_external_bluetooth_glib,pstglia/platform-external-bluetooth-glib,pstglia/platform-external-bluetooth-glib,antono/glib,tchakabam/glib,lukasz-skalski/glib,tchakabam/glib,tamaskenez/glib,gale320/glib,MathieuDuponchelle/glib,01org/android-bluez-glib,johne53/MB3Glib,pstglia/platform-external-bluetooth-glib,01org/android-bluez-glib,krichter722/glib,endlessm/glib,pstglia/external-bluetooth-glib,krichter722/glib,pstglia/external-bluetooth-glib,ieei/glib,johne53/MB3Glib,zsx/glib,gale320/glib,01org/android-bluez-glib,cention-sany/glib,mzabaluev/glib,Distrotech/glib,cosimoc/glib,mzabaluev/glib,justinkb/aosp-bluez.glib,cention-sany/glib,MathieuDuponchelle/glib,iConsole/Console-OS_external_bluetooth_glib,cosimoc/glib,darren-clark/android_platform_external_bluetooth_glib,endlessm/glib,zsx/glib,tchakabam/glib,bluez-android/glib,bluez-android/glib,cosimoc/glib,iConsole/Console-OS_external_bluetooth_glib,ieei/glib,Distrotech/glib,bluez-android/glib,MathieuDuponchelle/glib,iConsole/Console-OS_external_bluetooth_glib,ieei/glib,zsx/glib,krichter722/glib,cosimoc/glib,mzabaluev/glib,iConsole/Console-OS_external_bluetooth_glib,iConsole/Console-OS_external_bluetooth_glib,pstglia/platform-external-bluetooth-glib,djdeath/glib,djdeath/glib,gale320/glib,justinkb/aosp-bluez.glib,lukasz-skalski/glib,endlessm/glib,MathieuDuponchelle/glib,darren-clark/android_platform_external_bluetooth_glib,gale320/glib,01org/android-bluez-glib,johne53/MB3Glib,johne53/MB3Glib,antono/glib,pstglia/external-bluetooth-glib,djdeath/glib,gale320/glib,lukasz-skalski/glib,MathieuDuponchelle/glib,krichter722/glib,tamaskenez/glib,Distrotech/glib,darren-clark/android_platform_external_bluetooth_glib