Doc build fails on first run when using Unicode symbol entities

[mdavis]

The goal is to use Unicode symbols (specifically, in `reference_relationship.xml':

ST_Crosses(A, B) ⇔ (dim( I(A) ∩ I(B) ) < max( dim(I(A), I(B) ))) ∧ (a ∩ b ≠ a) ∧ (a ∩ b ≠ b)

On a clean install (running) autogen and then configure) the doc build fails:

make chunked-html

reference_relationship.xml:624: parser error : Entity 'hArr' not defined

If I remove the symbols, make chunked-html again, add the symbols back, and make again - it works.

[strk]

The failing command is:

grep -v '\&postgis_special;' postgis-out.xml | /usr/bin/xsltproc --novalid --path /usr/src/postgis/postgis/doc:/usr/src/postgis/postgis/doc -o list_3d_functions.xsl.xml xsl/list_3d_functions.xml.xsl -

[Sandro Santilli <strk@…>]

In 89a5f8f/git:

Properly encode dependencies of $XSL_GENERATED_SOURCES

References #5434

[strk]

Using a unicode character (utf8-encoded) like ⇔ instead of the entity seems to work fine for me

[mdavis]

This change now causes every run to fail on the Unicode entities.

[strk]

Closing as use of utf8 made it always pass, feel free to reopen otherwise