Haiku patches have been sent upstream and have been included in this release so it builds out of the box.
Only problem still is with two asm files in:
    scummvm/trunk/graphics/scaler/
Offending files are:
    hq2x_i386.asm
    hq3x_i386.asm
At the bottom of those 2 files you find the lines:

{{{
    %ifidn __OUTPUT_FORMAT__,elf
    section .note.GNU-stack noalloc noexec nowrite progbits
    %endif
}}}

These lines add an extra header GNU_STACK to the binary that Haiku can't handle (yet?) so it's safe to remove them.

Then just run ./configure --prefix, make and make install.