syntax: gentoo: highlight additional EAPI 7/8 variables

Add IDEPEND from EAPI 8, and also add more EAPI 7 roots so that all
of ROOT, EROOT, SYSROOT, ESYSROOT, and BROOT are supported.

Signed-off-by: David Michael <fedora.dm0@gmail.com>

syntax/extra/gentoo.nanorc

@@ -17,8 +17,8 @@ color green "-(eq|ne|gt|lt|ge|le)\>"
 ## Variables... official portage ones in red, all others in bright red:
 color brightred "\$[-0-9@*#?$!]" "\$[[:alpha:]_][[:alnum:]_]*"
 color brightred "\$\{[#!]?([-@*#?$!]|[0-9]+|[[:alpha:]_][[:alnum:]_]*)(\[([[:digit:]]|@)+\])?(([#%/]|:?[-=?+])[^}]*\}|\[|\})"
-color red "\<(EAPI|ARCH|HOMEPAGE|DESCRIPTION|IUSE|SRC_URI|LICENSE|SLOT|KEYWORDS|[BHPR]?DEPEND|PROVIDE|PROPERTIES|REQUIRED_USE|RESTRICT|USERLAND)\>"
-color red "\<(S|E?D|T|PV|PF|P|PN|PR|PVR|A|CATEGORY|DISTDIR|FILESDIR|EPREFIX|E?ROOT|WORKDIR)\>"
+color red "\<(EAPI|ARCH|HOMEPAGE|DESCRIPTION|IUSE|SRC_URI|LICENSE|SLOT|KEYWORDS|[BHIPR]?DEPEND|PROVIDE|PROPERTIES|REQUIRED_USE|RESTRICT|USERLAND)\>"
+color red "\<(S|E?D|T|PV|PF|P|PN|PR|PVR|A|CATEGORY|DISTDIR|FILESDIR|EPREFIX|(B|E|E?SYS)?ROOT|WORKDIR)\>"
 color red "\<(AS|C(PP|XX)?|LD)FLAGS\>" "\<C(HOST|TARGET|BUILD)\>" "\<(MERGE_TYPE|REPLACING_VERSIONS|REPLACED_BY_VERSION)\>"
 color red "\<EBUILD_PHASE(_FUNC)?\>"
 color red "\<QA_((TEXTRELS|EXECSTACK|WX_LOAD)(_[a-zA-Z_0-9]+)?|DT_HASH|PRESTRIPPED)\>"