Support version names starting with non numeric characters

Not only version names like 4.0.0, but also version names like
v4.0.0 or tesseract-4.0.0 are now supported and give the same
GENERIC_MAJOR_VERSION = 4.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

configure.ac

@@ -43,7 +43,7 @@ GENERIC_LIBRARY_NAME=tesseract
 
 # Release versioning. Get versions from PACKAGE_VERSION.
 AX_SPLIT_VERSION
-GENERIC_MAJOR_VERSION=$AX_MAJOR_VERSION
+GENERIC_MAJOR_VERSION=$(echo "$AX_MAJOR_VERSION" | $SED 's/^[[^0-9]]*//')
 GENERIC_MINOR_VERSION=$AX_MINOR_VERSION
 GENERIC_MICRO_VERSION=`echo "$AX_POINT_VERSION" | $SED 's/^\([[0-9]][[0-9]]*\).*/\1/'`