The Supreme Court has held, Regents of California v Bakke 438 U.S. 265, that a racial quota system is unconstitutional. The decision upheld the use of race as one of many factors, but ruled against setting aside positions that could only be filled by members of racial group ("forecloses consideration to persons like respondent"). To be constitutional, the practice must allow the possibility of hiring a person not in the racial group, thus they cannot require a person to be of a certain ethnicity, which is the situation you describe (but check the language of the ad since it probably states a preference, not a requirement). Preferences are found to be allowed in Grutter, Fisher, just as GPA or extramural activities can be considered. In Gratz it is emphasized that racial classifications are subject to strict scrutiny, thus must be narrowly tailored, and a system automatically awarding points or disqualifying applicants based on race is not narrowly tailored.
The EEOC has made available this non-opinion letter addressing faculty recruitment and the "especially encouraged" clause, which more or less says this, also pointing to 29 CFR 1607, i.e. addressing the Title VII issue. 29 CFR 1607.2(C), the statutory realization of Title VII, says
the use of recruiting procedures designed to attract members of a
particular race, sex, or ethnic group, which were previously denied
employment opportunities or which are currently underutilized, may be
necessary to bring an employer into compliance with Federal law, and
is frequently an essential element of any effective affirmative action
program; but recruitment practices are not considered by these
guidelines to be selection procedures
29 CFR 1607.3(B) requires that
Where two or more selection procedures are available which serve the
user's legitimate interest in efficient and trustworthy workmanship,
and which are substantially equally valid for a given purpose, the
user should use the procedure which has been demonstrated to have the
lesser adverse impact
which expresses the "least restrictive" concept of strict scrutiny.