version: Recognize data version 5.5.8

This was never used by any official Inno Setup release or even by any
commit in the git repo but there is at least one installer claiming it.

Version seems to be compatible with 5.5.7 so mark it as such to avoid
complications with the disambiguation of 5.5.7 and 5.6.0.

src/setup/version.cpp

@@ -170,6 +170,7 @@ const known_version versions[] = {
 	{ "Inno Setup Setup Data (5.5.7)",      /* ambiguous */ INNO_VERSION_EXT(5, 5,  7, 0), 0 },
 	{ "Inno Setup Setup Data (5.5.7) (u)",  /* ambiguous */ INNO_VERSION_EXT(5, 5,  7, 0), version::Unicode },
 	{ "Inno Setup Setup Data (5.5.7) (U)",  /* ambiguous */ INNO_VERSION_EXT(5, 5,  7, 0), version::Unicode },
+	{ "Inno Setup Setup Data (5.5.8) (u)", /* unofficial */ INNO_VERSION_EXT(5, 5,  7, 0), version::Unicode },
 	{ "" /* unknown 5.5.7 (u) variant */,   /* ambiguous */ INNO_VERSION_EXT(5, 5,  7, 1), 0 },
 	{ "" /* unknown 5.5.7 (u) variant */,   /* ambiguous */ INNO_VERSION_EXT(5, 5,  7, 1), version::Unicode },
 	{ "Inno Setup Setup Data (5.6.0)",                      INNO_VERSION_EXT(5, 6,  0, 0), 0 },