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>

 many ports hit this warning:

 ../sysdeps/unix/sysv/linux/check_native.c:46: warning: implicit declaration of function 'memset'

 ../sysdeps/unix/sysv/linux/check_native.c:46: warning: implicit declaration of function 'memset'

 snipped from suse

 diff -durN glibc-2.10.1.orig/sysdeps/unix/sysv/linux/check_native.c glibc-2.10.1/sysdeps/unix/sysv/linux/check_native.c

 --- glibc-2.10.1.orig/sysdeps/unix/sysv/linux/check_native.c	2007-11-24 04:12:17.000000000 +0100

 +++ glibc-2.10.1/sysdeps/unix/sysv/linux/check_native.c	2009-11-13 00:50:11.000000000 +0100

 @@ -23,6 +23,7 @@

  #include <stddef.h>

  #include <stdint.h>

  #include <stdlib.h>

 +#include <string.h>

  #include <time.h>

  #include <unistd.h>

  #include <net/if.h>