just replace:
#include <alloca.h>

with this:
#include <malloc.h>

this works for me. but next u will have another error:
cc vm/vm.c
vm/vm.c: In function 'TrVM_load':
vm/vm.c:371:43: warning: comparison between signed and unsigned integer expressi
ons
vm/vm.c: In function 'TrVM_interpret':
vm/vm.c:328:1: error: unable to find a register to spill in class 'SIREG'
vm/vm.c:328:1: error: this is the insn:
(insn 178 173 179 8 vm/vm.c:183 (parallel [
(set (reg:SI 2 cx [3049])
(const_int 0 [0x0]))
(set (reg/f:SI 1 dx [orig:3047 D.4445 ] [3047])
(plus:SI (reg:SI 3041)
(reg:SI 2 cx [3045])))
(set (reg/f:SI 0 ax [orig:3048 argv ] [3048])
(plus:SI (reg/v/f:SI 3 bx [orig:3030 argv ] [3030])
(reg:SI 2 cx [3045])))
(set (mem:BLK (reg:SI 3041) [0 A32])
(mem:BLK (reg/v/f:SI 3 bx [orig:3030 argv ] [3030]) [0 A32]))
(use (reg:SI 2 cx [3045]))
]) 656 {rep_movqi} (expr_list:REG_DEAD (reg:SI 2 cx [3045])
(expr_list:REG_DEAD (reg/v/f:SI 3 bx [orig:3030 argv ] [3030])
(expr_list:REG_UNUSED (reg:SI 2 cx [3049])
(expr_list:REG_UNUSED (reg/f:SI 0 ax [orig:3048 argv ] [3048])
(expr_list:REG_UNUSED (reg/f:SI 1 dx [orig:3047 D.4445 ] [30
47])
(nil)))))))
vm/vm.c:328: confused by earlier errors, bailing out
make: ** [vm/vm.o] Error 1

i'm using MinGW 4.5.1 from DevKit (DevKit-tdm-32-4.5.1-20101214-1400-sfx.exe) on Wwindows 7 x64.