make sure that the same compiler flags are used too

Good point - I now recall being tripped up by different optimization levels in the past.
However, I think the OP has probably already followed that advice by having built the executable with: 
gcc -s -O2 -DWIN32 -fwrapv -fno-strict-aliasing -mms-bitfields -o fite
+st.exe fitest.c -lfreeimage

[download]
Maybe there's some other pertinent option that has been omitted. We can't tell unless we see the output of perl -V:ccflags

There must be a Makefile somewhere created by Inline::C

Also a good point - it's usually under the ./_Inline/build directory, but you'll need to configure the Inline::C script with CLEAN_AFTER_BUILD => 0 to prevent the Makefile being automatically deleted when the compilation successfully completes.

Cheers,
Rob

In reply to Re^2: Errors using DLL from Inline C with 32-bit Perl by syphilis
in thread Errors using DLL from Inline C with 32-bit Perl by vr

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.