complibs/cloog: fix linking with libm

In Ubuntu 11.04 and 11.10, the default options for ld have changed.
--no-copy-dt-needed-entries and --as-needed are now enabled by default, which
causes errors like:

[EXTRA] Checking CLooG/ppl
[DEBUG] ==> Executing: 'make' '-j3' '-s' 'check'
[ALL ] Making check in .
[ALL ] config.status: creating include/cloog/cloog-config.h
[ALL ] config.status: include/cloog/cloog-config.h is unchanged
[ALL ] libtool: link: i686-build_pc-linux-gnu-gcc -Wall -fomit-frame-pointer
-pipe -o cloog cloog.o -L/<snip>/build/static/lib ./.libs/libcloog.a -lm
/<snip>/build/static/lib/libppl_c.a /<snip>/build/static/lib/libpwl.a
/<snip>/build/static/lib/libppl.a /<snip>/build/static/lib/libgmpxx.a
/<snip>/build/static/lib/libgmp.a -lstdc++
[ALL ] /usr/bin/ld: /<snip>/build/static/lib/libppl.a(MIP_Problem.o):
undefined reference to symbol 'sqrt@@GLIBC_2.0'
[ALL ] /usr/bin/ld: note: 'sqrt@@GLIBC_2.0' is defined in DSO
/usr/lib/gcc/i686-linux-gnu/4.6.1/../../../i386-linux-gnu/libm.so so try adding
it to the linker command line
[ALL ] /usr/lib/gcc/i686-linux-gnu/4.6.1/../../../i386-linux-gnu/libm.so:
could not read symbols: Invalid operation
[ALL ] collect2: ld returned 1 exit status
[ERROR] make[2]: *** [cloog] Error 1
[ERROR] make[1]: *** [check-recursive] Error 1

See:
https://wiki.ubuntu.com/NattyNarwhal/ToolchainTransition

This patch fixes these errors by placing '-lm' at the right place on the command
line as libppl requires libm when linking cloog.

Signed-off-by: "Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>

 http://sourceware.org/ml/binutils/2007-07/msg00401.html

 http://sourceware.org/bugzilla/show_bug.cgi?id=4970

 diff -durN binutils-2.20.1.orig/configure binutils-2.20.1/configure

 --- binutils-2.20.1.orig/configure	2010-03-03 14:59:02.000000000 +0100

 +++ binutils-2.20.1/configure	2010-08-17 19:32:05.000000000 +0200

 @@ -6466,6 +6466,7 @@

    *-*-mingw* | *-*-cygwin ) RPATH_ENVVAR=PATH ;;

    *) RPATH_ENVVAR=LD_LIBRARY_PATH ;;

  esac

 +RPATH_ENVVAR="cant_touch_this_nah_nah_nah"

  # On systems where the dynamic library environment variable is PATH,

  # gcc/ will put dynamic libraries into a subdirectory to avoid adding