RISC-V: Also, fixed more ld testcases for --with-arch and --with-abi

Well these testcases cannot be fixed by .option norvc simply, that is because
current linker needs to check mapping symbols before doing any rvc relaxations,
riscv-non-isa/riscv-elf-psabi-doc#393

Once we support the above features, we can revert this patch.

Author: Nelson Chu

ld/testsuite/ld-riscv-elf/pcgp-relax-01-norelaxgp.d

@@ -1,5 +1,6 @@
 #source: pcgp-relax-01.s
-#ld: --no-relax-gp --relax
+#as: -march=rv64i
+#ld: --no-relax-gp --relax -m[riscv_choose_lp64_emul]
 #objdump: -d -Mno-aliases
 
 .*:[ 	]+file format .*

ld/testsuite/ld-riscv-elf/pcgp-relax-01.d

@@ -1,5 +1,6 @@
 #source: pcgp-relax-01.s
-#ld: --relax
+#as: -march=rv64i
+#ld: --relax -m[riscv_choose_lp64_emul]
 #objdump: -d -Mno-aliases
 
 .*:[ 	]+file format .*

ld/testsuite/ld-riscv-elf/relax-max-align-gp.d

@@ -1,5 +1,6 @@
 #source: relax-max-align-gp.s
-#ld:
+#as: -march=rv64i
+#ld: -m[riscv_choose_lp64_emul]
 #objdump: -d
 
 .*:[ 	]+file format .*

ld/testsuite/ld-riscv-elf/relro-relax-lui.d

@@ -1,5 +1,6 @@
 #source: relro-relax-lui.s
-#ld: -zrelro --relax
+#as: -march=rv64i
+#ld: -zrelro --relax -m[riscv_choose_lp64_emul]
 #objdump: -d -Mno-aliases
 
 .*:[ 	]+file format .*

ld/testsuite/ld-riscv-elf/variant_cc-now.d

@@ -1,6 +1,7 @@
 #source: variant_cc-1.s
 #source: variant_cc-2.s
-#ld: -shared --hash-style=sysv -Ttext 0x8000 -z now
+#as: -march=rv64i -mabi=lp64
+#ld: -shared --hash-style=sysv -Ttext 0x8000 -z now -m[riscv_choose_lp64_emul]
 #readelf: -rsW
 
 Relocation section '.rela.plt' at .*

ld/testsuite/ld-riscv-elf/variant_cc-shared.d

@@ -1,6 +1,7 @@
 #source: variant_cc-1.s
 #source: variant_cc-2.s
-#ld: -shared --hash-style=sysv -Ttext 0x8000
+#as: -march=rv64i -mabi=lp64
+#ld: -shared --hash-style=sysv -Ttext 0x8000 -m[riscv_choose_lp64_emul]
 #readelf: -rsW
 
 Relocation section '.rela.plt' at .*