[AD] Problem with debug version and install_allegro autodetection macro

[Grzegorz Adam Hankiewicz <gradha@xxxxxxxxxx>]

Working on Pyallegro I managed to get the python module linked
against a different version of the C library. When install_allegro's
library version autodetection kicked in I got a strange assert in
debug mode. Here's the callstack:

 Assert failed at line 466 of src/allegro.c

 Program received signal SIGABRT, Aborted.
 [Switching to Thread -1209669952 (LWP 16856)]
 0xb7e897c7 in raise () from /lib/tls/libc.so.6
 (gdb) bt
 #0  0xb7e897c7 in raise () from /lib/tls/libc.so.6
 #1  0xb7e8b06b in abort () from /lib/tls/libc.so.6
 #2  0xb7a371f9 in al_assert (file=0xb7ae20b1 "src/allegro.c", line=466) at src/allegro.c:569
 #3  0xb7a36ee5 in get_executable_name (output=0xbfffebc0 "]", size=1024) at src/allegro.c:466
 #4  0xb7a55e0f in find_allegro_resource (
     dest=0xbffff110 "\200\016å·\004óÿ¿\024óÿ¿¸çá·ô?ù·\200Xù·@domain.hidÿÿÿÿÿÿ\214v¹·hñÿ¿:Ô\006\b\200v¹·\224óÿ¿»\a\021\bdóÿ¿", 
     resource=0xb7ae24bd "allegro.cfg", ext=0x0, datafile=0x0, objectname=0x0, envvar=0x0, subdir=0x0, size=1024) at src/file.c:1170
 #5  0xb7a48677 in init_config (loaddata=-1) at src/config.c:241
 #6  0xb7a4ab38 in get_config_text (msg=0xb7b2c920 "Library version mismatch") at src/config.c:1317
 #7  0xb7b20fc5 in alpy_install_allegro (self=0x0, args=0x0) at system.h:83
 #8  0x080fdc0a in PyCFunction_Call ()
 #9  0x080ab654 in PyEval_CallObjectWithKeywords ()
 #10 0x080a9a0e in Py_MakePendingCalls ()
 #11 0x080ab78d in PyEval_CallObjectWithKeywords ()
 #12 0x080ab54c in PyEval_CallObjectWithKeywords ()
 #13 0x080a9a0e in Py_MakePendingCalls ()
 #14 0x080ab78d in PyEval_CallObjectWithKeywords ()
 #15 0x080ab54c in PyEval_CallObjectWithKeywords ()
 #16 0x080a9a0e in Py_MakePendingCalls ()
 #17 0x080aa59c in PyEval_EvalCodeEx ()
 #18 0x080acd99 in PyEval_EvalCode ()
 #19 0x080d8eeb in PyRun_FileExFlags ()
 #20 0x080d869f in PyRun_SimpleFileExFlags ()
 #21 0x08054e95 in Py_Main ()
 #22 0x080549eb in main ()
 (gdb) f 7
 #7  0xb7b20fc5 in alpy_install_allegro (self=0x0, args=0x0) at system.h:83
 warning: Source file is more recent than executable.
 
 83       int dll_v = _get_allegro_version(); /* This comes from the DLL. */
 (gdb) f 3
 #3  0xb7a36ee5 in get_executable_name (output=0xbfffebc0 "]", size=1024) at src/allegro.c:466
 466      ASSERT(system_driver);
 (gdb) print system_driver
 $1 = (SYSTEM_DRIVER *) 0x0

Funny thing is I r'grepped for "version mismatch" and couldn't
find it anywhere...