Disable threads in a few tests

[• rafael]

Summary

Because of https://bugs.llvm.org/show_bug.cgi?id=32942 some tests take a long time to run. Right now running

./bin/llvm-lit --time-tests -sv ~/llvm/lld/test/ELF

takes 7.08s, the slowest tests being

2.77s: lld :: ELF/many-alloc-sections.s
6.15s: lld :: ELF/many-sections.s

with this patch the same command takes 2.37s and the slowest tests are

1.40s: lld :: ELF/many-alloc-sections.s
1.47s: lld :: ELF/many-sections.s

[davide]

LGTM. Please add a comment explaining why we pass -no-threads for the future reader.
FWIW, I hit the same issue on my machine and I'm glad you fixed it :)

[ruiu]

Did you know why that test takes that much time with threading?

[ruiu]

LGTM with a comment describing threads are disabled for this test because it's too slow otherwise.

test/ELF/many-alloc-sections.s

 // RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t.o
 // RUN: echo "SECTIONS { . = SIZEOF_HEADERS; .text : { *(.text) } }" > %t.script
-// RUN: ld.lld -T %t.script %t.o -o %t
+// RUN: ld.lld -T %t.script %t.o -o %t --no-threads
 // RUN: llvm-readobj -t %t | FileCheck %s
 
 // Test that _start is in the correct section.
 // CHECK:      Name: _start
 // CHECK-NEXT: Value: 0x120
 // CHECK-NEXT: Size: 0
 // CHECK-NEXT: Binding: Global
 // CHECK-NEXT: Type: None

test/ELF/many-sections.s

 // RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t
 // RUN: llvm-readobj -t %t | FileCheck  %s
 
 // Verify that the symbol _start is in a section with an index >= SHN_LORESERVE.
 // CHECK:      Name: _start
 // CHECK-NEXT: Value: 0x0
 // CHECK-NEXT: Size: 0
 // CHECK-NEXT: Binding: Global
 // CHECK-NEXT: Type: None
 // CHECK-NEXT: Other: 0
 // CHECK-NEXT: Section: dm (0xFF00)
 
 
-// RUN: ld.lld %t -o %t2
+// RUN: ld.lld %t -o %t2 --no-threads
 // RUN: llvm-readobj -t %t2 | FileCheck --check-prefix=LINKED %s
 
 // Test also with a linker script.
 // RUN: echo "SECTIONS { . = SIZEOF_HEADERS; .text : { *(.text) } }" > %t.script
-// RUN: ld.lld -T %t.script %t -o %t2
+// RUN: ld.lld -T %t.script %t -o %t2 --no-threads
 // RUN: llvm-readobj -t %t2 | FileCheck --check-prefix=LINKED %s
 
 // Test that _start is in the correct section.
 // LINKED:      Name: _start
 // LINKED-NEXT: Value: 0x0
 // LINKED-NEXT: Size: 0
 // LINKED-NEXT: Binding: Global
 // LINKED-NEXT: Type: None