gcc-4.8: fix compiling GCC when /usr/lib/libstdc++.so is present

gcc-4.8: fix compiling GCC when /usr/lib/libstdc++.so is present

libtool is picking up libstdc++.so from /usr/lib when trying to link
libasan due to libstdc++.la containing libdir="/usr/lib". If compiling
for x86 and the host has 64-bit /usr/lib/libstdc++.so, the compilation
fails linking libasan with:
/usr/lib/libstdc++.so: could not read symbols: File in wrong format

To resolve this, patch libtool to look for the library in the path the
.la is contained in rather than use the libdir which usually points to
a host path.

[YOCTO #4879]

(From OE-Core rev: ec95dfeea1f17eb232563e105085852058a86c0b)

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>