Revert "Rename unicode_combining_table to unicode_width_table"

This reverts commit eb0d0d2.

After I had committed eb0d0d2 and 78ab944, I decided to add
a sanity check for a "can't happen" scenario just to be cautious.
It turned out that it already happened in the official Unicode source
data, namely that a character can be both wide and a combining
character. This fact renders the aforementioned commits unnecessary,
so revert both of them.

Discussion: https://www.postgresql.org/message-id/CAFBsxsH5ejH4-1xaTLpSK8vWoK1m6fA1JBtTM6jmBsLfmDki1g%40mail.gmail.com

Author: j-naylor

src/common/unicode/Makefile

@@ -18,7 +18,7 @@ LIBS += $(PTHREAD_LIBS)
 # By default, do nothing.
 all:
 
-update-unicode: unicode_norm_table.h unicode_width_table.h unicode_normprops_table.h unicode_norm_hashfunc.h
+update-unicode: unicode_norm_table.h unicode_combining_table.h unicode_normprops_table.h unicode_norm_hashfunc.h
 	mv $^ ../../../src/include/common/
 	$(MAKE) normalization-check
 
@@ -35,7 +35,7 @@ unicode_norm_hashfunc.h: unicode_norm_table.h
 unicode_norm_table.h: generate-unicode_norm_table.pl UnicodeData.txt CompositionExclusions.txt
 	$(PERL) generate-unicode_norm_table.pl
 
-unicode_width_table.h: generate-unicode_width_table.pl UnicodeData.txt
+unicode_combining_table.h: generate-unicode_combining_table.pl UnicodeData.txt
 	$(PERL) $^ >$@
 
 unicode_normprops_table.h: generate-unicode_normprops_table.pl DerivedNormalizationProps.txt

src/common/unicode/generate-unicode_width_table.pl renamed to src/common/unicode/generate-unicode_combining_table.pl

@@ -15,7 +15,7 @@
 my $count = 0;
 
 print
-  "/* generated by src/common/unicode/generate-unicode_width_table.pl, do not edit */\n\n";
+  "/* generated by src/common/unicode/generate-unicode_combining_table.pl, do not edit */\n\n";
 
 print "static const struct mbinterval combining[] = {\n";
 

src/common/wchar.c

@@ -644,7 +644,7 @@ mbbisearch(pg_wchar ucs, const struct mbinterval *table, int max)
 static int
 ucs_wcwidth(pg_wchar ucs)
 {
-#include "common/unicode_width_table.h"
+#include "common/unicode_combining_table.h"
 
 	/* test for 8-bit control characters */
 	if (ucs == 0)

src/include/common/unicode_width_table.h renamed to src/include/common/unicode_combining_table.h

@@ -1,4 +1,4 @@
-/* generated by src/common/unicode/generate-unicode_width_table.pl, do not edit */
+/* generated by src/common/unicode/generate-unicode_combining_table.pl, do not edit */
 
 static const struct mbinterval combining[] = {
 	{0x0300, 0x036F},