Cherrypick the WAL error logging from the pre-3.7.5 line into a branch
for version 3.7.2.  Include the sqlite3_vsnprintf() interface.  This
checkin is intended for debugging and not for release.

FossilOrigin-Name: 6549e7672bcbac0bca6cef96c4d4a42998ba3ba9

• install-sh[diff]
• manifest[diff]
• manifest.uuid[diff]
• src/printf.c[diff]
• src/sqlite.h.in[diff]
• src/wal.c[diff]
• test/progress.test[diff]
• tool/mkopts.tcl[diff]