linking with -lX11 doesn't work??!!

[Carlos Carvalho <carlos@snfep1.if.usp.br>]

I tried to build an X program; the last line of the make was

cc foo.o bar.o .... etc ...   -lX11 -lm -s

However ld gave the following error:

ld: cannot open -lX11: No such file or directory

Here's what I have in /usr/X11R6/lib (the standard after installing
xbase and xtnd):

X11/            libX11.so.6.0*  libXaw.sa       libXmu.sa       libXt.so.6@
libFS.a         libXExExt.a     libXaw.so.6@    libXpm.a        libXt.so.6.0*
libICE.sa       libXIE.sa       libXaw.so.6.0*  libXpm.sa       libXtst.sa
libSM.sa        libXIE.so.6@    libXdmcp.a      libXpm.so.4@    liblbxXext.a
libX11.sa       libXIE.so.6.0*  libXext.sa      libXpm.so.4.6*  liboldX.a
libX11.so.6@    libXau.a        libXi.sa        libXt.sa

I had to use explicitely -L /usr/X11R6/lib -lX11 -lm -s to get the
program linked.

Did I miss something?

Carlos