+If the description of the system configuration printed by `configure'
+is not right, or if it claims some of the fatures or libraries are not
+available when you know they are, look at the `config.log' file for
+the trace of the failed tests performed by `configure' to check
+whether these features are supported. Typically, some test fails
+because the compiler cannot find some function in the system
+libraries, or some macro-processor definition in the system headers.
+
+Some tests might fail because the compiler should look in special
+directories for some header files, or link against optional
+libraries, or use special compilation options. You can force
+`configure' and the build process which follows it to do that by
+setting the variables CPPFLAGS, CFLAGS, LDFLAGS, LIBS, and CC before
+running `configure'. CPPFLAGS lists the options passed to the
+preprocessor, CFLAGS are compilation options, LDFLAGS are options used
+when linking, LIBS are libraries to link against, and CC is the
+command which invokes the compiler.
+
+Here's an example of a `configure' invocation, assuming a Bourne-like
+shell such as Bash, which uses these variables:
+
+ CPPFLAGS='-I/foo/myinclude' LDFLAGS='-L/bar/mylib' \
+ CFLAGS='-O3' LIBS='-lfoo -lbar' ./configure
+
+(this is all one long line). This tells `configure' to instruct the
+preprocessor to look in the `/foo/myinclude' directory for header
+files (in addition to the standard directories), instruct the linker
+to look in `/bar/mylib' for libraries, pass the -O3 optimization
+switch to the compiler, and link against libfoo.a and libbar.a
+libraries in addition to the standard ones.
+