Revert "[libc++][test] extend -linux-gnu XFAIL to cover all of the -linux targets (#129140)"

The effect of this commit is too broad and may affect also those
variants of Linux systems on which the affected test cases are known
to pass.

An alternative version of this commit will be prepared afresh.

This reverts commit c93dc58.

Author: pawosm-arm

libcxx/test/std/input.output/iostream.format/std.manip/setfill_wchar_max.pass.cpp

@@ -16,7 +16,7 @@
 
 // XFAIL: target={{.*}}-windows{{.*}} && libcpp-abi-version=1
 // XFAIL: target=armv{{7|8}}{{l?}}{{.*}}-linux-gnueabihf && libcpp-abi-version=1
-// XFAIL: target=aarch64{{.*}}-linux{{.*}} && libcpp-abi-version=1
+// XFAIL: target=aarch64{{.*}}-linux-gnu && libcpp-abi-version=1
 
 #include <iomanip>
 #include <ostream>

libcxx/test/std/re/re.alg/re.alg.match/awk.locale.pass.cpp

@@ -18,7 +18,7 @@
 
 // TODO: investigation needed
 // TODO(netbsd): incomplete support for locales
-// XFAIL: target={{.*}}-linux{{.*}}, netbsd, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, netbsd, freebsd
 // REQUIRES: locale.cs_CZ.ISO8859-2
 
 #include <regex>

libcxx/test/std/re/re.alg/re.alg.match/basic.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.alg/re.alg.match/ecma.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.alg/re.alg.match/extended.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.alg/re.alg.search/awk.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.alg/re.alg.search/basic.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.alg/re.alg.search/ecma.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.alg/re.alg.search/extended.locale.pass.cpp

@@ -22,7 +22,7 @@
 //                  regex_constants::match_flag_type flags = regex_constants::match_default);
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}, freebsd
+// XFAIL: target={{.*}}-linux-gnu{{.*}}, freebsd
 
 #include <regex>
 #include <cassert>

libcxx/test/std/re/re.traits/lookup_collatename.pass.cpp

@@ -23,7 +23,7 @@
 //   lookup_collatename(ForwardIterator first, ForwardIterator last) const;
 
 // TODO: investigation needed
-// XFAIL: target={{.*}}-linux{{.*}}
+// XFAIL: target={{.*}}-linux-gnu{{.*}}
 
 #include <regex>
 #include <iterator>