Merge multiboot section to .text section

All sections must be page aligned to set the right privileges, so we would many padding bytes otherwise.

src/arch/x86_64/linker.ld

@@ -19,14 +19,9 @@ ENTRY(start)
 SECTIONS {
   . = 1M;
 
-  .boot :
-  {
+  .text : {
     /* ensure that the multiboot header is at the beginning */
     KEEP(*(.multiboot))
-  }
-
-  .text :
-  {
     *(.text .text.*)
   }