[BOLT][TEST] Add section flags for .gcc_except_table

clang-10 complains about changed section flags in two tests:
- X86/shrinkwrapping.test
- X86/exceptions-args.test

Fix that by adding the missing flags.

Reviewed By: yota9

Differential Revision: https://reviews.llvm.org/D119014

Author: aaupov

bolt/test/X86/Inputs/exc4sw.S

@@ -124,7 +124,7 @@ _Z12never_throwsv:
 .LEHE3:
 	.cfi_endproc
 .LFE14:
-	.section	.gcc_except_table
+	.section	.gcc_except_table,"a",@progbits
 	.align 4
 .LLSDA14:
 	.byte	0xff
@@ -317,7 +317,7 @@ main:
 .LEHE14:
 	.cfi_endproc
 .LFE15:
-	.section	.gcc_except_table
+	.section	.gcc_except_table,"a",@progbits
 	.align 4
 .LLSDA15:
 	.byte	0xff

bolt/test/X86/Inputs/exc_args.s

@@ -157,7 +157,7 @@ _Z12never_throwsv:
 	ret
 	.cfi_endproc
 .LFE17:
-	.section	.gcc_except_table
+	.section	.gcc_except_table,"a",@progbits
 	.align 4
 .LLSDA17:
 	.byte	0xff
@@ -304,7 +304,7 @@ main:
 	ret
 	.cfi_endproc
 .LFE18:
-	.section	.gcc_except_table
+	.section	.gcc_except_table,"a",@progbits
 	.align 4
 .LLSDA18:
 	.byte	0xff