[lldb][tests] Fix passing pthread library to a linker for some API tests (#118530)

Specify ENABLE_THREADS := YES within test's Makefile instead of passing
-lpthread explicitly via the compiler's CFLAGS options.

Refactoring fix.

Co-authored-by: Vladimir Vereschaka <[email protected]>

Author: dzhidzhoev

lldb/test/API/commands/register/register/aarch64_sme_z_registers/za_dynamic_resize/Makefile

@@ -1,5 +1,6 @@
 C_SOURCES := main.c
 
-CFLAGS_EXTRAS := -march=armv8-a+sve+sme -lpthread
+CFLAGS_EXTRAS := -march=armv8-a+sve+sme
+ENABLE_THREADS := YES
 
 include Makefile.rules

lldb/test/API/commands/register/register/aarch64_sve_registers/rw_access_dynamic_resize/Makefile

@@ -1,5 +1,6 @@
 C_SOURCES := main.c
 
-CFLAGS_EXTRAS := -march=armv8-a+sve -lpthread
+CFLAGS_EXTRAS := -march=armv8-a+sve
+ENABLE_THREADS := YES
 
 include Makefile.rules

lldb/test/API/functionalities/process_save_core_minidump/Makefile

@@ -1,6 +1,6 @@
 CXX_SOURCES := main.cpp
 
-CFLAGS_EXTRAS := -lpthread
+ENABLE_THREADS := YES
 
 include Makefile.rules
 

lldb/test/API/tools/lldb-dap/threads/Makefile

@@ -1,4 +1,5 @@
 C_SOURCES := main.c
-CFLAGS_EXTRAS := -lpthread
+
+ENABLE_THREADS := YES
 
 include Makefile.rules