tests: skip on s390x

lld isn't being built nor shipped for this architecture, unlike many
other LLVM components. Make tests aware of their relevancy.

tests/basic/main.fmf

@@ -2,6 +2,10 @@ summary: Test lld with clang
 test: "$WITH_SCL ./test.sh"
 require: []
 adjust:
+  - because: lld is not shipped for s390x
+    enabled: false
+    when: arch == s390x
+
   # Common requirements when LLVM is not SCL-ized
   - require+:
       - clang

tests/build-gating-alternatives.fmf

@@ -19,6 +19,10 @@ adjust:
       and trigger != build
     enabled: false
 
+  - because: lld is not shipped for s390x
+    enabled: false
+    when: arch == s390x
+
   - because: "When testing SCL-ized LLVM, the collection must be enabled first"
     environment+:
       WITH_SCL: "scl enable llvm-toolset-13.0"

tests/build-gating.fmf

@@ -19,6 +19,10 @@ adjust:
       and trigger != build
     enabled: false
 
+  - because: lld is not shipped for s390x
+    enabled: false
+    when: arch == s390x
+
   - because: "When testing SCL-ized LLVM, the collection must be enabled first"
     environment+:
       WITH_SCL: "scl enable llvm-toolset-13.0"

tests/gcc-compat-basic/main.fmf

@@ -3,6 +3,10 @@ test: "$WITH_SCL ./test.sh"
 require:
   - gcc
 adjust:
+  - because: lld is not shipped for s390x
+    enabled: false
+    when: arch == s390x
+
   # Common requirements when LLVM is not SCL-ized
   - require+:
       - lld

tests/ld-alternative/main.fmf

@@ -6,6 +6,10 @@ tag:
 require:
   - binutils
 adjust:
+  - because: lld is not shipped for s390x
+    enabled: false
+    when: arch == s390x
+
   # Common requirements when LLVM is not SCL-ized
   - require+:
       - lld

tests/lit-tests/main.fmf

@@ -3,6 +3,10 @@ test: "$WITH_SCL ./test.sh"
 duration: 30m
 require: []
 adjust:
+  - because: lld is not shipped for s390x
+    enabled: false
+    when: arch == s390x
+
   # Common requirements when LLVM is not SCL-ized
   - require+:
       - lld