Optimize v2/v3 read queries

This solves a performance regression introduced in v0.6 when the read
algorithm was improved. The changes are too move the string comparision
of contig until after we've checked all integer based conditions.
Second, and more impactful, exit the intersection check early if the
regions have moved pasted the record. The regions are sorted so this
early exit is safe.

libtiledbvcf/src/read/reader.cc

@@ -626,17 +626,18 @@ bool Reader::process_query_results_v3() {
     for (; j < read_state_.regions.size(); j++) {
       const auto& reg = read_state_.regions[j];
 
-      // If the region does not match the contig skip
-      if (reg.seq_name != std::get<2>(contig_info))
-        continue;
-
       const uint32_t reg_min = reg.seq_offset + reg.min;
       const uint32_t reg_max = reg.seq_offset + reg.max;
 
       // If the vcf record is not contained in the region skip it
-      if (end < reg_min || real_start > reg_max)
+      if (real_start > reg_max)
         continue;
 
+      // If the regions (sorted) are starting past the end of the record we can
+      // safely exit out, as we will not intersect this record anymore
+      if (end < reg_min)
+        break;
+
       // Unless start is the real start (aka first record) then if we skip for
       // any record greater than the region min the goal is to only capture
       // starts which are within 1 anchor gap of the region start on the lower
@@ -649,6 +650,10 @@ bool Reader::process_query_results_v3() {
       if (anchor_gap < reg_min && start < reg_min - anchor_gap)
         continue;
 
+      // If the region does not match the contig skip
+      if (reg.seq_name != std::get<2>(contig_info))
+        continue;
+
       // If we overflow when reporting this cell, save the index of the
       // current region so that we restart from the same position on the
       // next read. Otherwise, we will re-report the cells in regions with
@@ -733,9 +738,14 @@ bool Reader::process_query_results_v2() {
       const uint32_t reg_max = reg.seq_offset + reg.max;
 
       // If the vcf record is not contained in the region skip it
-      if (real_end < reg_min || start > reg_max)
+      if (start > reg_max)
         continue;
 
+      // If the regions (sorted) are starting past the end of the record we can
+      // safely exit out, as we will not intersect this record anymore
+      if (real_end < reg_min)
+        break;
+
       // Unless start is the real start (aka first record) then if we skip for
       // any record greater than the region min the goal is to only capture
       // starts which are within 1 anchor gap of the region start on the lower
@@ -748,6 +758,10 @@ bool Reader::process_query_results_v2() {
       if (anchor_gap < reg_min && start < reg_min - anchor_gap)
         continue;
 
+      // If the region does not match the contig skip
+      if (reg.seq_name != std::get<2>(contig_info))
+        continue;
+
       // If we overflow when reporting this cell, save the index of the
       // current region so that we restart from the same position on the
       // next read. Otherwise, we will re-report the cells in regions with