[torstenvl]

In assembler, the function prologue has to set up the stack frame with enough space to store local variables. Having all local variable declarations come at the beginning of the function was an extension of that - keeping C closer to assembler and perhaps making compilation conceptually easier. With modern optimizing compilers, though, we're not necessarily directly translating to assembler line for line, and might optimize out some variables entirely, so it doesn't matter as much.

EDIT: Looks like beagle3 beat me to it while I got coffee.