gio/Makefile.am: Filter out gcontenttype.c for MSVC builds
gio/Makefile.am: Filter out gcontenttype.c for MSVC builds

gcontenttype.c was split into gcontenttype.c and gcontenttype-win32.c
in commit 32192ee9 ("Split gcontenttype.c"), so we don't want to include
gcontenttype.c in the Visual C++ build as it is no longer a source file
meant for Windows.

Thanks to Thomas H.P. Anderson for pointing this out.

mzabaluev/glib,lukasz-skalski/glib,ieei/glib,MathieuDuponchelle/glib,endlessm/glib,Distrotech/glib,gale320/glib,mzabaluev/glib,krichter722/glib,ieei/glib,cosimoc/glib,gale320/glib,gale320/glib,krichter722/glib,mzabaluev/glib,cention-sany/glib,ieei/glib,lukasz-skalski/glib,cosimoc/glib,krichter722/glib,johne53/MB3Glib,cention-sany/glib,djdeath/glib,gale320/glib,tchakabam/glib,tamaskenez/glib,ieei/glib,endlessm/glib,tchakabam/glib,ieei/glib,tamaskenez/glib,krichter722/glib,cosimoc/glib,Distrotech/glib,tchakabam/glib,Distrotech/glib,gale320/glib,cosimoc/glib,Distrotech/glib,johne53/MB3Glib,cention-sany/glib,tamaskenez/glib,MathieuDuponchelle/glib,tamaskenez/glib,MathieuDuponchelle/glib,johne53/MB3Glib,lukasz-skalski/glib,tamaskenez/glib,mzabaluev/glib,MathieuDuponchelle/glib,tchakabam/glib,endlessm/glib,tchakabam/glib,cention-sany/glib,johne53/MB3Glib,krichter722/glib,cention-sany/glib,djdeath/glib,djdeath/glib,johne53/MB3Glib,lukasz-skalski/glib,djdeath/glib,endlessm/glib,johne53/MB3Glib,MathieuDuponchelle/glib,mzabaluev/glib,endlessm/glib,Distrotech/glib,lukasz-skalski/glib,cosimoc/glib,djdeath/glib