synclient.c: Replace old index() function with C89-standard strchr()
synclient.c: Replace old index() function with C89-standard strchr()

Fixes Solaris compiler warnings of:
"synclient.c", line 152: warning: implicit function declaration: index
"synclient.c", line 152: warning: improper pointer/integer combination: op "="

Signed-off-by: Alan Coopersmith <ea3248f8c2440b9439894eab21ef26209b22bacf@oracle.com>
Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>

mad-s/xf86-input-synaptics-absolute,mad-s/xf86-input-synaptics-absolute