diff hunk pattern: fix misconverted "\{" tex macro introducers

Pointed out by Brandon Casey.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

diff.c

@@ -1409,10 +1409,10 @@ static const struct funcname_pattern_entry builtin_funcname_pattern[] = {
 	  "|"
 	  "^(.*=[ \t]*(class|record).*)$",
 	  REG_EXTENDED },
-	{ "bibtex", "(@[a-zA-Z]{1,}[ \t]*\{{0,1}[ \t]*[^ \t\"@',\\#}{~%]*).*$",
+	{ "bibtex", "(@[a-zA-Z]{1,}[ \t]*\\{{0,1}[ \t]*[^ \t\"@',\\#}{~%]*).*$",
 	  REG_EXTENDED },
 	{ "tex",
-	  "^(\\\\((sub)*section|chapter|part)\\*{0,1}\{.*)$",
+	  "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",
 	  REG_EXTENDED },
 	{ "ruby", "^[ \t]*((class|module|def)[ \t].*)$",
 	  REG_EXTENDED },