[lldb] Fix linker flags in lldb tests

This is a fixup to #93808,
which used LDFLAGS instead of the correct LD_EXTRAS

Author: felipepiovezan

lldb/test/API/commands/target/basic/Makefile

@@ -4,7 +4,7 @@
 # EXE := b.out
 
 ifndef PIE
-	LDFLAGS := -no-pie
+	LD_EXTRAS := -no-pie
 endif
 
 include Makefile.rules

lldb/test/API/lang/c/global_variables/Makefile

@@ -3,7 +3,7 @@ C_SOURCES := main.c
 DYLIB_NAME := a
 DYLIB_C_SOURCES := a.c
 ifndef PIE
-	LDFLAGS := -no-pie
+	LD_EXTRAS := -no-pie
 endif
 
 include Makefile.rules

lldb/test/API/lang/cpp/char8_t/Makefile

@@ -1,7 +1,7 @@
 CXX_SOURCES := main.cpp
 CXXFLAGS_EXTRAS := -std=c++2a -fchar8_t
 ifndef PIE
-	LDFLAGS := -no-pie
+	LD_EXTRAS := -no-pie
 endif
 
 include Makefile.rules