Make popcount bit-masks stricter

Each bit run is upto the right shift count, so the each mask does not
need more upper bits.

internal/bits.h

@@ -398,9 +398,9 @@ rb_popcount32(uint32_t x)
 #else
     x = (x & 0x55555555) + (x >> 1 & 0x55555555);
     x = (x & 0x33333333) + (x >> 2 & 0x33333333);
-    x = (x & 0x0f0f0f0f) + (x >> 4 & 0x0f0f0f0f);
-    x = (x & 0x001f001f) + (x >> 8 & 0x001f001f);
-    x = (x & 0x0000003f) + (x >>16 & 0x0000003f);
+    x = (x & 0x07070707) + (x >> 4 & 0x07070707);
+    x = (x & 0x000f000f) + (x >> 8 & 0x000f000f);
+    x = (x & 0x0000001f) + (x >>16 & 0x0000001f);
     return (unsigned int)x;
 
 #endif
@@ -428,9 +428,9 @@ rb_popcount64(uint64_t x)
     x = (x & 0x5555555555555555) + (x >> 1 & 0x5555555555555555);
     x = (x & 0x3333333333333333) + (x >> 2 & 0x3333333333333333);
     x = (x & 0x0707070707070707) + (x >> 4 & 0x0707070707070707);
-    x = (x & 0x001f001f001f001f) + (x >> 8 & 0x001f001f001f001f);
-    x = (x & 0x0000003f0000003f) + (x >>16 & 0x0000003f0000003f);
-    x = (x & 0x000000000000007f) + (x >>32 & 0x000000000000007f);
+    x = (x & 0x000f000f000f000f) + (x >> 8 & 0x000f000f000f000f);
+    x = (x & 0x0000001f0000001f) + (x >>16 & 0x0000001f0000001f);
+    x = (x & 0x000000000000003f) + (x >>32 & 0x000000000000003f);
     return (unsigned int)x;
 
 #endif