Seriously ... they do that ??
Assuming you're correct, it's laughable (in the sense of "deplorable and ridiculous") that debian would install Inline::C without ensuring that those requisite headers (and the C compiler) are also installed.
Actually, in any case, I find it laughable that linux distros in general install broken builds of perl by default. Why do they do that ? Can't they afford the extra space on a 400GB hard drive ?