i don't know what "plsdbug" is, but source compilation errors in random projects are rarely a libtool bug.  you should contact whoever maintains "lt-plsdbug.c".

While building an executable on a Windows 2000 system with the OS run-time DLL's (i.e. gcc -mno-cygwin) I get some compilation warnings:

gcc -mno-cygwin -g -O2 -o .libs/plsdbug.exe plsdbug.o main.o  c:/usr/local/lib/libepc.a -Lc:/oracle/ora10g/bin -lorasql9 -loran9 ../
../src/lib/.libs/libplsdbug.dll.a c:/usr/local/lib/libdbug.dll.a -Wl,--rpath -Wl,c:/usr/local/lib
creating plsdbug.exe
.libs/lt-plsdbug.c: In function `main':
.libs/lt-plsdbug.c:109: warning: passing arg 2 of `execv' from incompatible pointer type
.libs/lt-plsdbug.c: In function `check_executable':
.libs/lt-plsdbug.c:156: error: `S_IXOTH' undeclared (first use in this function)
.libs/lt-plsdbug.c:156: error: (Each undeclared identifier is reported only once
.libs/lt-plsdbug.c:156: error: for each function it appears in.)
.libs/lt-plsdbug.c:157: error: `S_IXGRP' undeclared (first use in this function)