sqlite3.pc strikes again

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

There is still a problems with sqlite3.pc.  It's generated with wrong
CC invocation.  On an Ubuntu host, where there's no
/usr/include/stdarg.h the build fails with:

--- sqlite3.pc ---
In file included from <stdin>:1:0:
/home/uwe/work/netbsd/ro/src/external/public-domain/sqlite/lib/../dist/sqlite3.h:35:67:
 fatal error: stdarg.h: No such file or directory

The following

-           ${CC} -E -I${SRCDIR} - | tail -1 | tr -d '"') && \
+           ${CC} ${CPPFLAGS} -E - | tail -1 | tr -d '"') && \

seems to fix it, since --sysroot is picked up from CPPFLAGS, but I'm
not sure if it's entirely correct.

-uwe