sqlite: avoid use of unsupported -Ofast CFLAGS

sqlite: avoid use of unsupported -Ofast CFLAGS

sqlite3 refuses to be built with -ffast-math (a side effect of -Ofast) when it
falls back to implementing its own isnan() function.

sqlite3.c: In function ‘sqlite3IsNaN’:
sqlite3.c:28554:3: error: #error SQLite will not work correctly with the -ffast-math option of GCC.

To work around this, when -Ofast is used replace with -O3.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>