sqlcipher: fix build for xtensa

The sqlcipher package generates libraries that are too large for the xtensa
default placement of literals in a dedicated section. Use
-mtext-section-literal to place literals in the text section.

Fixes:
http://autobuild.buildroot.net/results/921/92116c2837e4c449919e7a0ab9aebd6abb1cbaf1/



Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>