rpm: Fix error.h handing properly on musl

rpm: Fix error.h handing properly on musl

Ignoring configure fragments when error.h does not exist on system
leaves eflutils half configured, which is seen when gold linker is
enabled because librpm does not have proper dependencies added,
therefore add error.h for non-glibc case and include it when glibc is
not used.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>