soup-http-input-stream: use a list of SoupBuffers instead a custom buffer
soup-http-input-stream: use a list of SoupBuffers instead a custom buffer

We store now a list of SoupBuffers pending to be read. That would save us
several realloc() and memcpy() if the client does not read from the stream
quickly enough.

https://bugzilla.gnome.org/show_bug.cgi?id=659255

Distrotech/libsoup,Distrotech/libsoup,jwendell/libsoup,Distrotech/libsoup,fanc999/libsoup,fanc999/libsoup,jwendell/libsoup,jwendell/libsoup,fanc999/libsoup,Distrotech/libsoup,fanc999/libsoup,fanc999/libsoup,jwendell/libsoup,jwendell/libsoup,Distrotech/libsoup