* gnu/packages/databases.scm (firebird)[source]: Add patches.
[arguments]: Add custom phase when building for riscv64-linux to force
the bootstrap phase to occur.
[native-inputs]: When building for riscv64-linux add autoconf, automake
and libtool.
* gnu/packages/patches/firebird-riscv64-support-pt1.patch,
gnu/packages/patches/firebird-riscv64-support-pt2.patch: New files.
* gnu/local.mk (dist_patch_DATA): Register them.
