Refactor SCRAM code to dynamically handle hash type and key length

Applying: WIP SCRAM-SHA-512
Using index info to reconstruct a base tree...
M	src/backend/libpq/auth-scram.c
M	src/backend/libpq/auth.c
M	src/backend/libpq/crypt.c
M	src/backend/libpq/hba.c
M	src/backend/utils/misc/guc_tables.c
M	src/common/scram-common.c
M	src/include/common/scram-common.h
M	src/include/libpq/crypt.h
M	src/include/libpq/hba.h
M	src/include/libpq/scram.h
M	src/interfaces/libpq/fe-auth-scram.c
M	src/interfaces/libpq/fe-auth.c
M	src/interfaces/libpq/fe-auth.h
M	src/test/authentication/t/001_password.pl
Falling back to patching base and 3-way merge...
Auto-merging src/test/authentication/t/001_password.pl
CONFLICT (content): Merge conflict in src/test/authentication/t/001_password.pl
Auto-merging src/interfaces/libpq/fe-auth.h
CONFLICT (content): Merge conflict in src/interfaces/libpq/fe-auth.h
Auto-merging src/interfaces/libpq/fe-auth.c
CONFLICT (content): Merge conflict in src/interfaces/libpq/fe-auth.c
Auto-merging src/interfaces/libpq/fe-auth-scram.c
CONFLICT (content): Merge conflict in src/interfaces/libpq/fe-auth-scram.c
Auto-merging src/include/libpq/scram.h
Auto-merging src/include/libpq/hba.h
Auto-merging src/include/libpq/crypt.h
CONFLICT (content): Merge conflict in src/include/libpq/crypt.h
Auto-merging src/include/common/scram-common.h
Auto-merging src/common/scram-common.c
Auto-merging src/backend/utils/misc/guc_tables.c
Auto-merging src/backend/libpq/hba.c
Auto-merging src/backend/libpq/crypt.c
CONFLICT (content): Merge conflict in src/backend/libpq/crypt.c
Auto-merging src/backend/libpq/auth.c
Auto-merging src/backend/libpq/auth-scram.c
CONFLICT (content): Merge conflict in src/backend/libpq/auth-scram.c
Patch failed at 0001 WIP SCRAM-SHA-512

error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config advice.mergeConflict false"