alsa-lib: fix uClibc builds

alsa-lib: fix uClibc builds

Currently alsa-lib fails to build on uClibc:

parser.c: In function 'snd_tplg_build_file':
parser.c:262:35: error: 'S_IRUSR' undeclared (first use in this function)
   open(outfile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
                                   ^
parser.c:262:35: note: each undeclared identifier is reported only once for each function it appears in
parser.c:262:45: error: 'S_IWUSR' undeclared (first use in this function)
   open(outfile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
                                             ^
parser.c: In function 'snd_tplg_build':
parser.c:330:35: error: 'S_IRUSR' undeclared (first use in this function)
   open(outfile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
                                   ^
parser.c:330:45: error: 'S_IWUSR' undeclared (first use in this function)
   open(outfile, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
                                             ^
Makefile:390: recipe for target 'parser.lo' failed

Fix this by adding an upstream fix as a backport.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>